Genesis 4:7

7. Shalt thou not be accepted Rather, is there not an uplifting, that is, of the countenance . The downcast, sullen look is not a mark of him that doeth well .

Sin lieth at the door In the Hebrew sin is a feminine noun, and lieth is a masculine participal, because, says Keil, with evident allusion to the serpent, “sin is personified as a wild beast, lurking at the door of the human heart, and eagerly desiring to devour his soul . ” 1 Peter 5:8. But we cannot, with Keil and others, understand that which follows, unto thee shall be his desire, as referring also to sin personified, for the words as used can scarcely justify the paraphrase: sin, lying at the door of thy heart, has strong desire to enter in and control thee; nevertheless, if thou do well, thou shalt obtain the mastery, and rule over sin. The better interpretation is that which refers the pronouns his and him to Abel. The Lord thus assures Cain that he has nothing to fear from Abel, whose תשׁוקה , desire, (tender and loyal devotion,) is strong and fervent towards him as his elder brother, and, therefore, certain to attempt no interference with Cain’s right of primogeniture to rule over him, and thus enjoy all the privileges of his natural pre-eminence .