Musannaf Ibn Abi Shayba 33:23

Muhammad ibn Fudayl narrated to us, from Layth, from Mujahid, who said: When David (Dawud) committed the sin—and his sin was only that when he saw her affair, he isolated her and did not approach her—the two litigants came to him. They climbed over the wall into the prayer niche. When he saw them, he stood up to them and said, "Get out from me! What has brought you two to me?" They said, "We only wish to speak to you with a few words. This is my brother; he has ninety-nine ewes, and I have one ewe, and he wants to take it from me." David said, "By Allah, he is more deserving of having his [nose] broken from here to here," meaning from his nose to his chest. The man said, "This is David, and he has done it." David realized that he [the man] meant him by that, and he recognized his sin. He fell prostrate for forty days and forty nights. His sin was written on his hand, and he would look at it so as not to be heedless, until the herbs grew around him from his tears, covering his head. After forty days, he cried out, "The forehead is sore, and the eye has dried up, and David has not had anything returned to him regarding his sin." It was called out to him, "Are you hungry so that you may be fed? Or naked so that you may be clothed? Or oppressed so that you may be helped?" He let out a sob that caused the herbs that were there to wither, as he did not mention his sin. At that, he was forgiven. When the Day of Resurrection comes, his Lord will say to him, "Be in front of Me." He will say, "O my Lord, my sin, my sin." He will say to him, "Be behind Me." He will say, "O my Lord, my sin, my sin." He will say to him, "Take hold of My foot," and he will take hold of His foot.