881 – Anas, may Allah be pleased with him, related: Two men sneezed in the presence of the Prophet, peace and blessings be upon him. He blessed (performed tashmīt for) one of them but did not bless the other. The one who had not been blessed said, “So-and-so sneezed and you blessed him, whereas I sneezed and you did not bless me.” The Prophet replied, “He praised Allah, whereas you did not.” Agreed upon.

[Explanation]
Imam al-Nawawī, may Allah have mercy on him, writes in Riyāḍ al-Ṣāliḥīn under the heading “The recommendation to bless a sneezer when he praises Allah and the etiquette of sneezing and yawning”: Sneezing is from Allah and is beloved to Him, as comes in the ḥadīth of Abū Hurayrah in which the Prophet, peace and blessings be upon him, said, “Indeed, Allah loves sneezing.” The reason is that sneezing indicates liveliness and agility; you will notice that a person feels invigorated after he sneezes. Allah loves the energetic, earnest servant. In the authentic narration the Prophet also said, “The strong believer is more beloved to Allah than the weak believer, though both possess goodness.”