Midrasch zu Bereschit 37:32

And Reuven returned to the pit. Where was he? Rabbi Eliezer and Rabbi Yehoshua [disagree]. Rabbi Eliezer said from his sackcloth and fast, when he finished he returned and looked into the pit, as it is written "And Reuven returned to the pit". The Holy One of Blessing said: "there has never been a time ever when a person who sinned before me did teshuva. You were the first one to do teshuva, and [as a reward] I swear that your grandson will stand and open the way to teshuva. Who is this? Hoshea, as it says: "return Israel unto Hashem, your God". "And they took the striped coat and they slaughtered a goat" (Gen. 37:31). Why a goat? Because its blood is similar to human blood. "And they sent the cloak etc" (Gen. 37:32). Rabbi Yochanan said that the Holy One of Blessing said to Yehuda, 'you said to your father 'do you recognize it?' I swear that Tamar will say about you, "do you recognize it?" (Gen. 38:25). "He recognized it and said: 'it is my son's cloak."(Gen. 37:33) I don't know what I am seeing. "A wild animal must have eaten him!' (Gen. 37:33) Rav Huna said the Holy Spirit was on him, when he said he a wild animal - this was Potiphar's wife.