Such Is the Power of Teshuvah
When Adam learned from his son Kayin that teshuvah could soften even a harsh decree, he broke into the song of the Shabbos day.
After Kayin killed his brother Hevel, Hashem sentenced him to wander the earth. The Midrash relates that when Kayin went out from before Hashem, his father Adam met him on the road and was surprised to see him at peace. "What happened with your judgment?" Adam asked.
"I did teshuvah," Kayin answered, "and my sentence was eased."
Adam was stunned. He struck his own face and cried out, "So great is the power of teshuvah, and I did not know it." At that moment he stood and began to sing, "Mizmor shir l'yom haShabbos, a psalm, a song for the Shabbos day. It is good to give thanks to Hashem." The word lehodos means both to give thanks and to admit. Adam was singing about the joy of returning to Hashem.
Rebbi Levi teaches that Adam was the first to say this mizmor, but his generation forgot it. Generations later Moshe Rabbeinu came and restored it, and so it is counted among his psalms. The first letters of its opening words, he points out, can be rearranged to spell l'Moshe, to Moshe.
Each Friday night, when Jews around the world sing Mizmor Shir L'Yom HaShabbos at Kabbalas Shabbos, they are repeating the song of a father who discovered, through his own son, that no fall is the end of the story.
Source: Midrash Bereishis Rabbah 22:13; English: The Sefaria Midrash Rabbah (2022).
This Friday night, when you reach Mizmor Shir L'Yom HaShabbos, slow down for the words "tov l'hodos laShem," it is good to give thanks to Hashem. Let them also mean, as Adam meant them, it is good to admit and come back. Think of one thing from this week you would like to do differently, and quietly hand it to Hashem as you sing. You may find, as Adam did, that coming back feels less like a burden and more like a song.