Sayyiduna Abu Sa'id Khudri and Sayyiduna Abu Hurairah (may Allah be pleased with them both) reported that the Messenger of Allah (peace and blessings of Allah be upon him) saw phlegm on the wall of the (Prophet's) Mosque, so he scraped it off with a pebble. Then the Messenger of Allah (peace and blessings of Allah be upon him) said: "When any of you spits (during prayer), he should not spit in front of him nor to his right side, but rather to his left side or under his foot."