"But the stranger that dwelleth with you shall be unto you as one born among you, and thou shalt love him as thyself; for ye were strangers in the land of Egypt: I am the LORD your God."
Leviticus 19:34 (KJV)
"Rabbi Yohanan ben Zakkai said, Go forth and see which is the good way to which a man should cleave. Rabbi Eliezar said, A good eye; Rabbi Joshua said, A good friend; Rabbi Jose said, A good neighbor; Rabbi Simeon said, One who foresees the fruit of an action; Rabbi Elazar said, A good heart. Thereupon he said to them, I approve the words of Elazar ben Arach, rather than your words, for in his words yours are included."
Mishnah, Abot 2.13
"A certain heathen came to Shammai and said to him, Make me a proselyte, on condition that you teach me the whole Torah while I stand on one foot. Thereupon he repulsed him with the rod which was in his hand. When he went to Hillel, he said to him, What is hateful to you, do not do to your neighbor: that is the whole Torah; all the rest of it is commentary; go and learn."