Malik related to me from Nafi that when Abdullah ibn Umar sneezed
and someone said to him, "May Allah have mercy on you,"
(Yarhamuka'llah), he said, "May Allah have mercy on us and you, and
forgive us and you." (Yarhamuna'llah wa yaghfirlana wa lakum).
Muwatta Malik Book 54, Hadith 5