Imam Bukhari narrates: 'Abdullah bin Yusuf narrated to us the hadeeth, he said: Imam Malik informed us, from Nafi', from Hazrat 'Abdullah bin 'Umar (may Allāh be pleased with them both)

that the Messenger of Allāh ﷺ saw spit on the wall of the Qiblah, so he scraped it off, then turning towards the people he said: When any one of you prays, let him not spit in front of himself, because when he prays, Allāh is in front of him.