The Messenger of Allah ﷺ said, "If any of you spits in the mosque, let him bury it. If he cannot, let him spit into his garment."
حدثنا زيد بن الحباب أخبرني أبو مودود حدثني عبد الرحمن بن أبي حدرد قال سمعت
قال رسول الله ﷺ إذا بزق أحدكم في المسجد فليدفنه فإن لم يفعل فليبزق في ثوبه
Its isnad is sahih. Abu Mawdud is Abdul-Aziz bin Abu Sulayman Madani. We previously confirmed his reliability at 528, and we add here that he was deemed reliable by Ahmad, Ibn Main, Ibn Madini, and others, and Ibn Abu Hatim gave his biography at 2/2/384, as did Dulabi in al-Kuna 2:134.Mawdud is spelled with two dals, and in manuscript H it appears with a ra instead of the first dal, which is a clear printing error.Abdul-Rahman bin Abu Hadrad, with fatha on the ha and the ra, and between them a silent dal, ending in a dal, all unpointed letters, Aslami Madani, was a reliable follower. Ibn Hibban mentioned him in al-Thiqat, and Ibn Abu Hatim gave his biography at 2/2/228.This hadith will appear again at 8280, 10098, and 10902, all through the transmission of Abu Mawdud, with this same isnad, in similar wording, both at length and abridged. Abu Dawud narrated it at 477 from Qanabi, from Abu Mawdud, in wording similar to the coming narration at 8280. The meaning of the hadith is confirmed through other sahih routes from Abu Hurairah, see for example 7399.As for his statement "let him bury it," in two copies in the margin of manuscript M it reads "let him remove it far away," which agrees with Ibn Kathir's narration in Jami al-Masanid wal-Sunan at this passage.