(99) باب كَيْفَ تَشْمِيتُ الْعَاطِسِ
Abu Hurairah reported the prophet (May peace be upon him) as saying:
When one of you sneezes, he should say: "Praise be to Allah in every circumstance," and his brother or his companion should say: "May Allah have mercy on you!" And he should then reply: "May Allah guide you and set right your affairs."
Reference: Sunan Abi Dawud 5033
In-book reference: Book 43, Hadith 261
English translation: Book 42, Hadith 5015