صحيح البخاري Sahih Bukhari كتاب الأدب The Book of Al-Adab (Good Manners)
بَابُ الْحَمْدِ لِلْعَاطِسِ:

(123) Chapter. To say Al-Hamdu-lillah (praise be to Allah) on sneezing.

1 hadith
Hadith 6221
حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ ، حَدَّثَنَا سُفْيَانُ ، حَدَّثَنَا سُلَيْمَانُ ، عَنْ أَنَسِ بْنِ مَالِكٍ رَضِيَ اللَّهُ عَنْهُ ، قَالَ : عَطَسَ رَجُلَانِ عِنْدَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، فَشَمَّتَ أَحَدَهُمَا وَلَمْ يُشَمِّتِ الْآخَرَ فَقِيلَ لَهُ ، فَقَالَ : " هَذَا حَمِدَ اللَّهَ ، وَهَذَا لَمْ يَحْمَدِ اللَّهَ " .
Narrated Anas bin Malik: Two men sneezed before the Prophet. The Prophet said to one of them, "May Allah bestow His Mercy on you," but he did not say that to the other. On being asked (why), the Prophet said, "That one praised Allah (at the time of sneezing), while the other did not praise Allah."
Hadith Reference Sahih Bukhari / The Book of Al-Adab (Good Manners) / Hadith: 6221
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة