What is hateful to you, do not to your neighbor. That is the whole Torah; the rest is commentary. Go and study it.
[d’`alakh sani l’khaverkha la ta`avid. Zo hi kol hatora kulahh, v’idakh peirusha hu: zil g’mor]
The Talmud (AD 200-500) Collection of Jewish rabbinical writings
Babylonian Talmud, Shabbat 31a (Rabbi Hillel)
(Noted elsewhere as tractate Shabbat 30a.) See also the Bible, Matthew 7:12.Alt. Trans.: "What is hateful to thee, do not unto thy fellow; this is the whole law. All the rest is a commentary to this law; go and learn it."