Al-Adab Al-Mufrad #1104
The People of the Book
Abu 'Uthman an-Nahdi said, "Abu Musa wrote to a Persian grandee
and greeted him in his letter. He was asked, 'Do you greet him when he
is an unbeliever?' He replied, 'He wrote to me and greeted me, so I have
answered him.'"
About Al-Adab Al-Mufrad
This hadith is #1104 from Al-Adab Al-Mufrad, in the Book of The People of the Book. Al-Adab Al-Mufrad contains 1,326 hadiths across 57 books.