“Let the evil one abandon his way, and the iniquitous person his [unholy] thoughts. Let him return to G-d and have mercy on him ('veyerachamahu')...” (Isaiah 55:7).

The simple meaning of this verse is that G-d will have mercy on the penitent sinner. However, the word "veyerachamahu" doesn’t specify who the beneficiary of the mercy is, thus leaving open the possibility of interpreting the verse to mean that the offender should have mercy on G-d.

The soul of every Jew is a part of G-d. The “piece” of G-d which forms the essence of the Jewish soul is not amputated from its source; rather, the soul can be compared to the bottom edge of the “divine rope.” Tug one end of a rope and the opposite end, no matter the length of the rope and the distance between the ends, will also follow along. So too, incredibly, the actions of the Jewish person, the bottom edge of the rope, affect G-d Himself. 

When a Jew sins, he sullies not only his or her own soul, but G-d also is dragged into the revolting world of sin and Kelipah. As Rabbi Schneur Zalman of Liadi writes (Tanya, chapter 24): “There is no greater exile than this. It is [a plunge] from a lofty roof [to a deep pit]... It is comparable to one who seizes the king’s head, drags it down, and dips his face in a privy full of dung — the ultimate in humiliation, even if he does it only for a moment.”

The sinner is therefore implored to have mercy on G-d and do Teshuvah for His sake.