Briefly, it is not only their fellow human beings that the beloved of God must treat with mercy and compassion; rather must they show forth the utmost LOVING-KINDNESS TO EVERY LIVING CREATURE. 
~Abdu'l-Baha, Writings of Abdu'l-Baha

Be ye the embodiments of justice and fairness amidst ALL CREATION. 
~ Bah'u'llh, The Kitb-i-Aqdas (Most Holy Book)

Buddhism

A state that is not pleasing or delightful to me, how could I inflict that upon another?
~ Samyutta Nikaya v. 353

All tremble at violence; all fear death. Putting oneself in the place of another, one should not kill nor cause another to kill.
~ Shakyamuni Buddha, Dhammapada

One is not a great one because one defeats or harms other living beings. One is so-called because one REFRAINS FROM DEFEATING OR HARMING OTHER LIVING BEINGS.
~ Shakyamuni Buddha, Dhammapada

Hurt not others with that which pains you yourself.
~ Buddhist Sutra Udanavarga 5,18

At the openings of ant hills, please have trustworthy men always put food and water, sugar and piles of grain.
~ Nagarjuna, Precious Garland, 249 - 50

All Buddhas and Bodhisattvas essentially practice the principle of great compassion. The suffering of living beings brings forth their great compassion. From this great compassion emerges the great wisdom, and with this great wisdom, they attain the ultimate enlightenment.
~ Shakyamuni Buddha, Avatamsaka Sutra

People who eat meat will fall into the horrible paths of transmigration and suffer boundless pain. People who eat meat will never succeed in getting any blessing or merit that they pray for. Meat-eaters cause the celestial beings to avoid them and other sentient beings to be afraid of them.
~ Shakyamuni Buddha, Surangama Sutra

Kasyapa asked the Buddha: "Why did the Lord previously allow Bhiksus to eat the 'three pure meats' or even 'nine pure meats'?" The Buddha said, "It was so instituted following the need of the occasion, and as gradual steps in the actual segregation from eating meat."
~ Shakyamuni Buddha, Nirvana Sutra

All the saints abhorred eating blood or flesh???. Celestial beings never go near people who eat meat as their mouth always has a foul smell???. Meat is not good, meat is unclean; meat eating generates evils and destroys merits and blessings. All the saints denounce eating meat!
~ Shakyamuni Buddha, Lankavatara Sutra

I forbid all meat eating, regardless of whether the animal dies naturally or is killed. I have never allowed my disciples to eat meat, and I will not allow in the present or future.
~ Shakyamuni Buddha, Lankavatara Sutra

All sentient beings came from the same origin. Through myriad reincarnations, all sentient beings have been relatives of each other. How can we eat the meat of our relatives?
 ~ Shakyamuni Buddha, Lankavatara Sutra

People who eat meat are destroying the great merciful seed of their own Buddha nature, and any sentient beings seeing them would leave them. Therefore, all Bodhisattvas (spiritual practitioners) must refrain from eating the flesh of any sentient beings, as this will incur boundless sin.
~ Shakyamuni Buddha, Brahmajala Sutra

 Do to others as you want them to do to you. 
~Luke 6:31, Holy Bible

Let the law of kindness show no limits. SHOW A LOVING CONSIDERATION FOR ALL GOD'S CREATURES.
~ Religious Society of Friends (Quakers), General Advices

Blessed are the merciful, for they will be shown mercy.
~ Matthew 5:7, Holy Bible

It is contrary to human dignity to cause animals to suffer and die.
~Catechism of the Catholic Church, 2418

Woe to the shepherds who only take care of themselves! Should not the shepherds take care of the flock?
~ Ezekiel 34:2-4, Holy Bible

Do not be among those who give themselves to wine-drinking, or among those who make themselves full with meat.
~ Proverbs 23:20, Holy Bible

Meats for the belly, and the belly for meats: but God shall destroy both it and them. Now the body is not for fornication, but for the Lord; and the Lord for the body.
~ 1st Corinthians 6:13, Holy Bible

To what purpose is the multitude of your sacrifices unto me? saith the LORD: I am full of the burnt offerings of rams, and the fat of fed beasts; and I DELIGHT NOT IN THE BLOOD OF BULLOCKS, OR OF LAMBS, OR OF HE GOATS???And when ye spread forth your hands, I will hide mine eyes from you: yea, when ye make many prayers, I will not hear: your hands are full of innocent blood. Put away the evil of your doings from before mine eyes; cease to do evil.
~ Isaiah 1:11, 15-16, Holy Bible

For I tell you truly, he who kills, kills himself, and who eats the flesh of slain beasts, eats of the body of death. For in his blood every drop of their blood turns to poison; in his breath their breath to stink; in his flesh their flesh to boils; in his bones their bones to chalk; in his bowels their bowels to decay; in his eyes their eyes to scales; in his ears their ears to waxy issue. And their death will become his death
~ The Essene Gospel of Peace, Book 1

KILL NOT, NEITHER EAT THE FLESH OF YOUR INNOCENT PREY, lest you become the slaves of Satan. For that is the path of sufferings, and it leads unto death. But do the will of God, that His angels may serve you on the way of life.
 ~ The Essene Gospel of Peace, Book 1

And God said, 'Behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in which is the fruit of a tree yielding seed; to you it shall be for meat. And to every beast of the earth, and to every fowl of the air, and to everything that creepeth upon the earth, wherein there is breath of life, I have given every green herb for meal and it was so.
 ~ Genesis 1:29-30, Holy Bible

But flesh with the life thereof, which is the blood thereof, shall ye not eat.
 ~ Genesis 9:4, Holy Bible

Thou shalt not kill.
 ~ Exodus 20:13, Holy Bible

Better is a dinner of herbs where love is, than a stalled ox and hatred therewith.
 ~ Proverbs: 15:17, Holy Bible

Jesus said, "I will have mercy, and not sacrifice."
~ Matthew 9:13 & 12:7, Holy Bible

St. Paul: "It is good neither to eat flesh, nor to drink wine, nor any thing whereby thy brother stumbleth, or is offended, or is made weak."
~ Romans 14:21, Holy Bible

BENEFIT LIVING CREATURES AND HUMAN BEINGS. Cultivate goodness and happiness.
~ Yin-chih-wen (Confucian-Taoist treatise)

What you do not want done to yourself, do not do to others.
~ Confucius, The Confucian Analects, Lunyu 12.2

Respect the old and cherish the young. EVEN INSECTS, GRASS AND TREES YOU MUST NOT HURT.
~ Attributed to Ko Hung, Confucian-Taoist treatise T'ai-shang-kan-ying p'ien

Those who want to know the truth of the universe SHOULD PRACTICE REVERENCE FOR ALL LIFE; this manifests as unconditional love and respect for oneself and all other beings.
~ Hua Hu Ching 51 

Buy captive animals and give them freedom.
~ Taoist teaching.  The Tract of the Quiet Way

Those who have forsaken the killing of all; those who are helpmates to all; those who are a sanctuary to all; those men are in the way of Heaven.
~ Hitopadesa (Hindu Text)

Ahimsa (non-violence) is the highest Dharma. Ahimsa is the best Tapas. Ahimsa is the greatest gift. Ahimsa is the highest self-control. Ahimsa is the highest sacrifice. Ahimsa is the highest power. Ahimsa is the highest friend. Ahimsa is the highest truth. AHIMSA IS THE HIGHEST TEACHING.
~ Mahabharat Shantiparva, 262.47

The mode of living which is founded upon a TOTAL HARMLESSNESS TOWARDS ALL CREATURES is the highest morality.
~ Mahabharata, Shantiparva 262.5-6

What is the good way? It is the path that reflects on how it may AVOID KILLING ANY CREATURE.
~ Tirukural, Verse 324

PROTECT BOTH OUR SPECIES, TWO-LEGGED AND FOUR-LEGGED. Both food and water for their needs supply. May they with us increase in stature and strength. Save us from hurt all our days, O Powers!
~ Rig Veda Samhita 10.37.11

May all beings look at me with a friendly eye. May I do likewise, and MAY WE ALL LOOK ON EACH OTHER WITH THE EYES OF A FRIEND.
~ Yajur Veda 36.18

 
Islam 

There is not an animal on the earth, nor a flying creature on two wings, BUT THEY ARE PEOPLE LIKE UNTO YOU.
~Qur'an, Al-An`am 6:38 

Whoever is KIND TO  ALL CREATURES OF GOD is kind to himself.
~ Prophet Mohammed, Hadith

TREAT OTHERS AS YOU WOULD BE TREATED.  What you like not for yourself, dispense not to others.
~ Abdullah Ansari, Islamic Sufi text

Seest thou not that it is Allah Whose praise all beings in the heavens and on earth do celebrate, and the birds of the air with wings outspread? Each one knows its own mode of prayer and praise, and ALLAH KNOWS WELL ALL THAT THEY DO.
~ Qur'an Sura Al-Nour, 41

A GOOD DEED DONE TO AN ANIMAL IS AS MERITORIOUS AS DONE TO HUMAN BEING, while an act of cruelty to an animal is as bad as an act of cruelty to a human being.
~ Prophet Mohammed, Hadith

ALL CREATURES ARE LIKE A FAMILY OF GOD: and He loves the most those who are the most
beneficent to His family.
~ Prophet Mohammed, Hadith

ALLAH WILL NOT GIVE MERCY  TO ANYONE, EXCEPT THOSE WHO GIVE MERCY  TO OTHER CREATURES. Where there is an abundance of vegetables, a host of angels will descend on that place.
~ Prophet Mohammed, Hadith

He who TAKES PITY EVEN ON A SPARROW AND SPARES ITS LIFE, ALLAH WILL BE MERCIFUL ON HIM on the Day of Judgement.
~ Prophet Mohammed, Hadith

THEIR FLESH AND THEIR BLOOD REACH NOT ALLAH, BUT THE DEVOTION from you reacheth Him. Thus have we made them subject unto you that ye may magnify Allah that He hath guided you. And give good tidings, O Mohammed, to the good.
~ Qur'an Sura Sura: AL-Hajj 37

At one time THE RASUL OF ALLAH SAID TO HIS COUSIN 'ALI, "O 'ALI, YOU SHOULD NOT EAT MEAT. If you eat meat for forty days, those qualities will come within you. Those actions will come within you. Their blood will come within you. Their qualities and their actions will come within you. Because of that, your human qualities will change, your compassionate qualities will change, the essence of your body will change. O 'Ali, you should not eat meat or flesh. You have to diminish that. Do not eat that."
~ Muhammad Raheem Bawa Muhaiyaddeen, Islamic Sufi saint

Therefore, neither does he [a sage] cause violence to others nor does he make others do so.
~ Acharanga Sutra 5.101-2.

A man should wander about TREATING ALL CREATURES AS HE HIMSELF would be treated.
~ Sutrakritanga 1.11.33

Those whose minds are at peace and who are free from passions do not desire to live at the expense of others.
~ Mahavira, Acharanga Sutra

ONE SHOULD NOT INJURE, SUBJUGATE, ENSLAVE, TORTURE, OR KILL ANY ANIMAL, LIVING BEING, ORGANISM, or sentient being. THIS DOCTRINE OF NONVIOLENCE IS IMMACULATE, IMMUTABLE, AND ETERNAL. Just as suffering is painful to you, in the same way it is painful, disquieting, and terrifying to all animals, living beings, organisms, and sentient beings.
~  Acharanga Sutra 4.25-26

Have BENEVOLENCE TOWARDS ALL LIVING BEINGS. 
~ Tattvartha Sutra 7.11

NON-INJURY TO LIVING BEINGS IS THE HIGHEST RELIGION.
~First Truth of Jainism, the maxim 'Ahimsa Paramo Dharmah'

THIS IS THE QUINTESSENCE OF WISDOM; NOT TO KILL ANYTHING. All breathing, existing, living sentient creatures should not be slain, nor treated with violence, nor abused, nor tormented, nor driven away. This is the pure unchangeable Law. Therefore, cease to injure living things.
~ Sutrakritanga 1.11.10-16

Then the LORD God said, "It is not good for the man to be alone. I WILL MAKE A HELPER WHO IS LIKE HIM."  So the LORD God formed out of the ground EACH WILD ANIMAL AND EACH BIRD of the sky, and brought each to the man to see what he would call it. 
~ Genesis 2:18-19, Talmud and Christian Old Testament, Holy Bible

What is hateful to you, do not do to others. 
~ Talmud, Shabbat 3id

I will make a covenant on behalf of Israel with the wild beasts, the birds of the air, and the things that creep on the hearths, that ALL LIVING CREATURES MAY LIE DOWN WITHOUT LIVING IN FEAR.
~Hosea, 2:18, Talmud and Old Testament, Holy Bible

The Jewish concept of tsa'ar ba'alei chaim is the OBLIGATION NOT TO CAUSE PAIN TO ANIMALS.
~ Code of Jewish Law

Sikhism

The highest religion is to rise to universal brotherhood; and to CONSIDER ALL CREATURES YOUR EQUALS.
~ Guru Nanak Dev, Jap Ji XXVIII

You say that THE ONE LORD IS IN ALL, so why do you kill chickens?
~ Guru Granth Sahib, 1350

Kabir says, TO USE FORCE IS TYRANNY, EVEN IF YOU CALL IT A RELIGIOUS SACRIFICE. When your account is called for in the Kingdom of God, what will your condition be then?
~ Guru Granth Sahib, 1374

Those mortals who consume marijuana, flesh and wine - no matter what pilgrimages, fasts and rituals they follow, they will all go to hell.
~ Guru Granth Sahib, 1377)

You kill living beings and worship lifeless things, at your very last moment, you will suffer terrible pain.
~ Guru Granth Sahib, 332

Bhagat Kabir says, that THE BEST FOOD IS EATING KICHREE (VEGETABLE) where nectar sweet is the salt. You eat hunted meat, but which animal is willing to have their head cut?
~ Guru Granth Sahib, 1374

Falsehood is my dagger and to EAT BY DEFRAUDING IS MEAT.
~ Guru Granth Sahib, 24

Avarice is a dog, falsehood the sweeper and CHEATING THE EATING OF MEAT.
~ Guru Granth Sahib, 15

The world eats dead carcasses, living by neglect and greed. Like a goblin, or a beast, they kill and eat the forbidden carcasses of meat. So control your urges, or else you will be seized by the Lord, and thrown into the tortures of hell.
~ Guru Granth Sahib,  723

You kill living beings, and call it a righteous action. Tell me, brother, what would you call an unrighteous action? You call yourself the most excellent sage; then who would you call a butcher?
~ Guru Granth Sahib, 1103

The Lord has given me this one understanding: ALL CREATURES, ALL LIVING THINGS BELONG TO ONE CREATOR, may I never forget this, Oh Lord.
~ Guru Nanak Dev, Guru Granth Sahib, Jap Ji Sahib, 2

Just as clothes stained with blood become impure, one CANNOT HAVE PURE CONSCIOUSNESS WHEN ONE CONSUMES BLOOD AND FLESH OF OTHER BEINGS.
~ Guru Nanak Dev, Guru Granth Sahib, 140

BE KIND TO ALL BEINGS - this is more meritorious than visiting and bathing at the 68 pilgrimage sites and the giving of charity.
~ Guru Granth Sahib, 136