Al-Adab Al-Mufrad #929

Abu Salih reported that the Prophet, may Allah bless him and grant him peace, said, "When one of you sneezes, he should say, 'Praise be to Allah.' When he says, 'Praise be to Allah, ' his brother or companion should say to him, 'May Allah have mercy on you.' Then let the person who sneezed say, 'May Allah guide you and put your affairs in order.'"