Musannaf Ibn Abi Shayba 33:396

Yazid ibn Harun narrated to us, he said: Hariz ibn Uthman narrated to us, from Nimran ibn Muhammad al-Raji, who said: Abu Ubaydah ibn al-Jarrah used to walk among the army while saying: "How many a person who whitens his garments is [actually] staining his religion! How many a person who honors his soul is [actually] debasing it! Hasten to [erase] the old evil deeds with new good deeds, for if one of you were to commit sins [filling the space] between the heaven and the earth, then performed a good deed, his good deeds would overcome his sins until they conquer them."