Hadith 1309
It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Spitting in the mosque is a sin, and its expiation is to bury it." In the narration of Ibn 'Ulayyah and Waki', instead of "al-buzaaq," the word "at-tafl" is used. The meaning is the same, that is, "to spit."