Genesis 38:9

This chapter gives us an account of Judah and his family, and such an account it is that one would wonder that, of all Jacob's sons, our Lord should spring out of Judah, Heb 7:14. If we were to form a character of him by this story, we should not say, "Judah, thou art he whom thy brethren shall praise," Gen 49:8. But God will show that his choice is of grace and not of merit, and that Christ came into the world to save sinners, even the chief, and is not ashamed, upon their repentance, to be allied to them, also that the worth and worthiness of Jesus Christ are personal, of himself, and not derived from his ancestors. Humbling himself to be "made in the likeness of sinful flesh," he was pleased to descend from some that were infamous. How little reason had the Jews, who were so called from this Judah, to boast, as they did, that they were not born of fornication! Joh 8:41. We have, in this chapter, I. Judah's marriage and issue, and the untimely death of his two eldest sons (Gen 38:1-11). II. Judah's incest with his daughter-in-law Tamar, without his knowing it (Gen 38:12-23). III. His confusion, when it was discovered (Gen 38:24-26). IV. The birth of his twin sons, in whom his family was built up (Gen 38:27, etc.).

38:9-10 Onan married Tamar, but was not willing to provide an heir for his brother. He would have sex with Tamar but not fulfill his responsibility to his dead brother (38:8).