Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.086B.
Section : Praising Allah when one sneezes or recalls to mind a blessing.
Rifa’ah ibn Rafi’ relates: “I prayed behind the Messenger of Allah, and I sneezed and said, ‘Praise be to Allah, a great deal of praise, beautiful and blessed, as our Lord loves and is pleased with.’ [Afterward,] the Messenger of Allah asked: ‘Who spoke during the salah?’ No one said anything. He asked again, and no one said anything. He asked again, and I said: ‘It was I, O Messenger of Allah!’ He then said: ‘By the One in whose hand is Muhammad’s soul, thirty some odd angels raced to get that phrase to raise it [to the Lord].'” This is related by an-Nasa’i and at-Tirmizhi, and by al-Bukhari with a different wording.