The Midrash relates that after this incident Kayin met his father, Adam, who inquired about his form of punishment. Kayin responded, “I performed repentance and came to an understanding (compromise) with my Maker.” This Midrash goes on to imply that Kayin was the first one to have performed the mitzvah of Teshuva. This is inconsistent, however, with a later Midrash in Parashas Vayeshev in which chazal relate that Hashem stated that Reuven is considered to have been the first one to have repented properly.
In order to respond to this question, we must first analyze Kayin’s repentance. The words that are used to describe his repentance are “I came to an understanding or compromise.” This attitude characterizes a different form of contrition. This is a repentance whose basis is compromise, motivated by a desire to escape punishment. Reuven’s repentance, in contrast, was so complete that it erased the blemish created by his offense. Such a teshuva guarantees complete disavowal of the sin.
What is the basic difference between their respective types of Teshuvos? What is the key to Reuven’s success and Kayin’s apparent failure? Kayin was undoubtedly brokenhearted from the brutal act of slaying his brother. His remorse was surely from the bottom of his heart. The focus of his contrition, however, was only the actual sin, not its source. One does not rise up and commit such a brutal act without collecting emotional ammunition. First there is jealousy, which eventually leads to hatred and conflict. Regarding these evils, Kayin did not repent. He only “compromised” for his present incursion, but not its origins. From this great compromise was born Tuval Kayin, whose profession was to fashion weapons of destruction. Reuven, however, searched for the origin of his sin, and was, therefore, able to repent totally to Hashem
