It is narrated from Hazrat Abu Basrah Ghifari (may Allah be pleased with him) that one day the Prophet (peace and blessings be upon him) said: "Tomorrow I will ride and go to the Jews, therefore do not initiate greeting them with Salam, and when they greet you with Salam, you should only say «وعليكم» ." So when we reached there and they greeted us with Salam, we only said «وعليكم» .