Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) saw phlegm in the direction of the qiblah in the mosque, so he cleaned it with his stick. Then he turned towards the people, and they could see intense anger on his blessed face. He (peace and blessings be upon him) asked, "Whose phlegm is this?" They all remained silent. He (peace and blessings be upon him) said, "Does any one of you like that when he is praying, a person comes and spits on his face?" The companions replied, "No, (no one would like that)." He (peace and blessings be upon him) said, "Indeed, Allah is in front of you in your prayers, so do not throw any filth in front of yourselves, but (if necessary) put it to your left or under your foot."