رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 881
The Book of Greetings
Saying "Al-Hamdulillah" When Sneezing, Its Reply, and Manners Relating to Sneezing and Yawning
وَعَنْ أَنَسٍ رَضِيَ اللَّهُ عَنْهُ قَالَ: عَطَسَ رَجُلاَنِ عِنْدَ النَّبِيِّ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ ، فَشَمَّتَ أَحَدَهُمَا وَلَمْ يُشَمِّتِ الآخَرَ، فَقَالَ الَّذِي لَمْ يُشَمِّتْهُ: عَطَسَ فُلاَنٌ فَشَمَّتَّهُ، وَعَطَسْتُ فلم تشمتني؟ فَقَالَ: هَذَا حَمِدَ اللَّهَ، وَإِنَّكَ لَمْ تَحْمَدِ اللَّهَ ((مُتَّفَقٌ عَلَيْهِ))
Anas (May Allah be pleased with him) reported: When two men sneezed in the presence of the Prophet (ﷺ), he responded to one with "Yarhamuk-Allah (may Allah have mercy on you)" and did not respond to the other. The latter said to him: "You invoked a blessing on this man but did not do so in my case." The Prophet (ﷺ) replied, "He praised Allah (i.e., he said 'Al-hamdu lillah') but you did not." [Al-Bukhari and Muslim].
Riyad as-Salihin, 881