I said prayer with the Messenger of Allah (ﷺ) and saw him spitting and rubbing it off with his shoe.
Sahih Muslim Book 5, Hadith 72
← Previous Hadith The Apostle of Allah (ﷺ) said: The deeds of my people, good and bad, were presented before me, and I found the removal of something objectionable from the road among their good deeds, and the sputum mucus left unburied in the mosque among their evil deeds.

Sahih Muslim Book 5, Hadith 71 Next Hadith → 'Abdullah b. Shakhkhir narrated it on the authority of his father that he said prayer with the Messenger of Allah (ﷺ), and he spat and then rubbed it off with his left shoe.

Sahih Muslim Book 5, Hadith 73