Muwatta Malik 234
موطأ مالك#234SahihThese are the words of a Successor — the generation after the Companions — not of the Prophet ﷺ.
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ رَجُلاً، عَطَسَ يَوْمَ الْجُمُعَةِ وَالإِمَامُ يَخْطُبُ فَشَمَّتَهُ إِنْسَانٌ إِلَى جَنْبِهِ فَسَأَلَ عَنْ ذَلِكَ سَعِيدَ بْنَ الْمُسَيَّبِ فَنَهَاهُ عَنْ ذَلِكَ وَقَالَ لاَ تَعُدْ .
Yahya related to me from Malik that he had heard that a man sneezed on the day of jumua while the imam was giving the khutba, and a man by his side asked Allah to bless him. Said ibn al Musayyab was asked about it and he forbade the man to do what he had done and said, "Don't do it again
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 5:10