Musnad Ahmad 26:82

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Ibrahim al-Taymi, from Al-Harith ibn Suwayd, and Al-A'mash, from 'Umarah, from Al-Aswad, they both said: Abdullah said: "Indeed, the believer sees his sins as if he is at the base of a mountain, fearing that it might fall upon him. And the wicked person sees his sins as a fly that landed on his nose, so he said with it like this, and it flew away." He said: And the Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah is more joyful with the repentance of one of you than a man who went out into a desolate, destructive land, with his riding beast, upon which was his provision, his food, his drink, and what sustains him. Then he lost it, so he went out in search of it until, when death overtook him, he said: 'I will return to the place where I lost it, and I will die there.' He said: So he returned, and his eyes overcame him (he fell asleep). He woke up, and there was his riding beast at his head, with his provision, his food, his drink, and what sustains him upon it." Then Abu Mu'awiyah said: They both said: Abdullah narrated to us two hadiths: one of them from himself, and the other from the Messenger of Allah (peace and blessings of Allah be upon him).