The Messenger of Allah ﷺ saw some phlegm on the qiblah wall of the mosque and scraped it off with his hand.
حدثنا عبد الصمد حدثنا حماد عن ثابت
أن رسول الله ﷺ رأى نخامة في قبلة المسجد فحكها بيده
Its isnad is sahih, mentioned previously at 13000.