Sunan Abi Dawud 484
سنن أبي داود#484Da'ifحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا الْفَرَجُ بْنُ فَضَالَةَ، عَنْ أَبِي سَعِيدٍ، قَالَ رَأَيْتُ وَاثِلَةَ بْنَ الأَسْقَعِ فِي مَسْجِدِ دِمَشْقَ بَصَقَ عَلَى الْبُورِيِّ ثُمَّ مَسَحَهُ بِرِجْلِهِ فَقِيلَ لَهُ لِمَ فَعَلْتَ هَذَا قَالَ لأَنِّي رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَفْعَلُهُ .
Narrated Wathilah ibn al-Asqa': AbuSa'id said: I saw Wathilah ibn al-Asqa' in the mosque of Damascus. He spat at the mat and then rubbed it with his foot. He was asked: Why did you do so? He said: Because I saw the Messenger of Allah (ﷺ) doing so
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: 2:94