Musnad Abu Ya'la al-Mawsili 106:51

Ja'far ibn Humayd al-Kufi narrated to us, Ubayd Allah ibn Iyad narrated to us, from his father, from al-Bara' who said: The Messenger of Allah (ﷺ) said: "How would you describe the joy of a man whose riding beast escaped from him, dragging its rein in a desolate land in which there is neither food nor drink, and upon it was his food and drink? He sought it until it became difficult for him, then it passed by the trunk of a tree and its rein became entangled, so he found it entangled in it." We said: "Intensely, O Messenger of Allah." The Messenger of Allah (ﷺ) said: "Allah is more joyful at the repentance of His servant than that man is with his riding beast."