מדרש אויף שמואל א 15:14

Psalm of Thanksgiving. Rabbi Yaakov said in the name of Rabbi Abbahu in the name of Rabbi Acha: "Let all nations give thanks to me," and I accept them, as it is said: "Every knee shall bow to Me, every tongue shall swear" (Isaiah 45:23). If every knee bows and every tongue swears to Me, I accept them. This is what Scripture says: "He who conceals his transgressions will not prosper" (Proverbs 28:13). He who conceals his transgressions is Adam, who said to God: "The woman whom You gave to be with me" (Genesis 3:12). He did not seek to do repentance, as it is said: "Lest he stretch out his hand" (Genesis 3:22). Rabbi Abba bar Kahana said: When the Holy One, blessed be He, said to him, "Do teshuva," he replied, "Lest." But "now" means teshuva, as it is said: "And now, Israel, what does the Lord your God ask of you but to fear Him?" (Deuteronomy 10:12). And "lest" means "no." He who conceals his transgressions will not prosper. "Whoever confesses and forsakes will be shown mercy" (Proverbs 28:13). This refers to Cain, as it is said: "And Cain went out from before the Lord" (Genesis 4:16). Rabbi Huna said in the name of Rabbi Chanina bar Yitzchak: He went out rejoicing, as it is said: "And Haman went out that day joyful and with a glad heart" (Esther 5:9). Adam met him and said to him, "What has happened with your judgment?" He replied, "I did teshuva and was forgiven." Adam said to him: "Good is to give thanks to the Lord" (Psalm 92:2). Another explanation of "He who conceals his transgressions": This refers to Saul, as it is said: "What is this bleating of sheep in my ears?" And Saul said, "They have brought them from the Amalekites" (1 Samuel 15:14-15). "Whoever confesses and forsakes will be shown mercy": This refers to David, who said: "I have sinned against the Lord; please take away the iniquity of Your servant" (2 Samuel 24:10). Immediately, God said to him: "The Lord has also put away your sin" (2 Samuel 12:13). Rabbi Simon and Rabbi Yehoshua ben Levi said in the name of Rabbi Chalfata: When a king of flesh and blood confesses, God gives him the benefit of the doubt. But when he does not confess, God does not give him the benefit of the doubt.