Sayyiduna Abu Dharr (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "The good and bad deeds of my Ummah were presented to me. Among the good deeds I saw the removal of something harmful from the road, and among the bad deeds I saw phlegm that someone had dropped in the mosque and that was not buried."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3590