A Jewish man passed by the Prophet, and said, “Death be upon you, O Muhammad.” Thereupon, Aisha said, “Death and curse be upon you!” But the Messenger of Allah forbade her and said: “Indeed, Allah is Gentle and loves gentleness.” (1) He also said: “When the People of the Book greet you, say: ‘And upon you.’” (2) It is also stated in Sahih al-Bukhari and Sahih Muslim that he said: “The People of the Book say, ‘Death be upon you.’ So when they greet you, say: ‘And upon you.’” (3)

If their greeting is ambiguous, then one must say, “And upon you,” for if he said “Peace,” then peace is upon him; and if he said “Death,” then death is upon him.

Question: Is it permissible to congratulate them, offer them condolences, visit their sick, or attend their funerals?

Answer: As for congratulating them on their religious festivals, this is unquestionably forbidden. Indeed, a person may not remain safe from falling into disbelief, because congratulating them on festivals of disbelief constitutes approval of them, and approving of disbelief is itself disbelief. This includes congratulating them on what is called Christmas, Easter, or the like. This is absolutely impermissible. Even if they congratulate us on our festivals, we do not congratulate them on theirs. The difference is that their congratulating us on our festivals is a congratulation upon what is true, whereas our congratulating them on their festivals is a congratulation upon what is false,