The Prophet ﷺ said, "When one of you sneezes, let him say, 'Praise be to Allah in every state.' Let the one who hears him say, 'May Allah have mercy on you,' and let him reply, 'May Allah guide you and set your affairs right.'"I asked him, "From Abu Ayub?"He said, "Yes."
حدثنا يحيى عن ابن أبي ليلى حدثني أخي عن أبي
عن النبي ﷺ قال إذا عطس أحدكم فليقل الحمد لله على كل حال وليقل له يرحمكم الله وليقل هو يهديكم الله ويصلح بالكم فقلت له عن أبي أيوب قال علي رضي الله عنه
Its isnad is hasan. Yahya is Ibn Saeed Qattan. Ibn Abu Layla is Muhammad bin Abdul-Rahman. His brother is Isa bin Abdul-Rahman.His statement was, "I said to him, 'From Abu Ayub?' He said, 'Ali.'" It appears that the question was from Imam Ahmad to his teacher, "Is this hadith from the hadith of Abu Ayub or from the hadith of Ali?" So he stated definitively to him that it was from the hadith of Ali.The reason for that is that Shubah narrated it from Muhammad bin Abdul-Rahman bin Abu Layla, from his brother Isa, from his father, from Abu Ayub. Tirmidhi likewise narrated it, in volume 4, pages 3-4, from Mahmud bin Ghaylan, from Abu Dawud Tayalisi, from Shubah, and also from Muhammad bin Muthanna, from Muhammad bin Jafar, from Shubah. Tirmidhi then said, "This is how Shubah narrated this hadith from Ibn Abu Layla, saying, 'From Abu Ayub, from the Prophet ﷺ.' Ibn Abu Layla was inconsistent regarding this hadith, sometimes saying, 'From Abu Ayub, from the Prophet ﷺ,' and sometimes saying, 'From Ali, from the Prophet ﷺ.'" He then narrated it from Muhammad bin Bashshar and Muhammad bin Yahya Thaqafi, both from Yahya Qattan, matching the isnad of Ahmad found here.I consider the narration of those who reported it as the hadith of Ali to be more sahih than the narration of Shubah, because Ali bin Mushir and Mansur bin Abu Aswad narrated it from Muhammad bin Abdul-Rahman in the same way as the narration of Yahya Qattan, as already mentioned in 972 and 973. Yet if the narration of Shubah is also preserved correctly, then both hadiths would be established, one from Ali and one from Abu Ayub, and we would not call this kind of thing inconsistency.The hadith of Abu Ayub, from the narration of Shubah, will come with two isnads in volume 5, page 422h.