I prayed with the Messenger of Allah ﷺ and saw him spit, then rub it with his sandal.
صليت مع رسول الله ﷺ فرأيته تنخع فدلكها بنغله.
Muslim narrated it in "the Mosques" chapter (554) from Ubaydullah bin Muaz Anbari, my father narrated to us, Kahmas narrated to us, from Yazid bin Abdullah bin Shikhir, from his father, and he mentioned it.He and Abu Dawud (482) both narrated it, from the hadith of Saeed Jariri, from Abu Ala Yazid bin Abdullah bin Shikhir, from his father, that he prayed with the Prophet ﷺ. He said, "He spat and rubbed it with his left sandal."As for Abu Dawud, he narrated it in a similar manner, and he also narrated it from Abu Ala, from Mutarrif, who is his brother, from his father, who said, "I came to the Messenger of Allah ﷺ while he was praying, and he spat beneath his left foot."