"What you hate, do not do to your friend." -- Shabbos 31a
"Do not seek revenge or bear a grudge against anyone among your people, but love your neighbor as yourself. I am the LORD." -- Vayikra 19:18
"Hillel and Shammai received the Torah from them. Hillel said: 'Be of the disciples of Aaron, loving peace and pursuing peace, loving your fellow creatures and bringing them close to the Torah.' " -- Avot 1:12
"If you have done your neighbor a little wrong, let it be in your eyes great; if you have done him much good, let it be in your eyes little; if he has done you a little good, let it be in your eyes great; if he has done you a great wrong, let it be in your eyes little." -- Avot 1:6, Avot de Rabbi Nathan ch 41
"He who says, 'What is mine is yours and what is yours is thine own'—he is a saintly man." -- Avot 5:13
"A love without rebuke is no real love." -- Bereishit Rabbah, ch 54, section 3
"The highest form of wisdom is kindness." -- Berachot 17a
Shimon the Righteous was one of the last survivors of the Great Assembly. He used to say: "On three things the world is sustained: on the Torah, on the (Temple) service, and on deeds of loving kindness." -- Avot 1:2
"The world is built with chesed (loving-kindness)." -- Tehillim 89:3
"Let us not become weary in doing good, for at the proper time we will reap a harvest if we do not give up." -- Galatians 6:9