Genesis 38:6

It would seem that Tamar, the daughter-in-law of Judah, was a daughter of the Canaanites, like her mother-in-law. Abraham had been most careful about the choice of a wife for Isaac; she was not to be a daughter of the Canaanites. But Isaac plainly did not step in when Esau took wives from the daughters of the Hittites, though they caused him grief. Isaac charged Jacob not to take a wife from the daughters of Canaan. Yet Jacob does not seem to have been troubled when Judah joined himself to the Canaanites through Shuah, or when he took Tamar to be the wife of his eldest son, Er. There is much instruction for Christians in all this: how very careful we should be about our associations, both for ourselves and for our children.

Er was the firstborn of Judah's strength. His father named him, and his name may mean "watchful." Er, it seems, became watchful for chances to do evil… Er deceived himself. But was he not simply following his father? To bring up children in an evil world is not easy. When parents introduce their children to the things of this present evil age, they will find them throwing themselves into it with great energy. And that world lies in ruin, far from God.

Tamar had the right to be the mother of Judah's heir. He kept that right from her, and in doing so blamed her for the death of his sons. He did not blame his own sons for any wrong. Judah's favouritism toward his own family blinded him to the truth… Many people today let family ties sway their judgment in important matters.

Genesis 38 completely interrupts the story of Joseph. It would seem that the shameful story of Judah is told here to heighten in our minds the way Joseph stood firm under a temptation of the same kind. Judah appears to have been among the better behaved of Jacob's sons. Yet the practices that marked him and his family were evil, and it seems they were accepted as nothing very unusual.

It was Judah, not Reuben or any other of the tribal heads, who proposed the sale of Joseph. Now he showed in his own house the evil that drew down curse on curse. In the end he had to admit the sad shame of Tamar — more righteous than himself, though he had sentenced her to die by fire. Yet by this guilty Judah, and by Tamar, came He who cleanses from all sin by His blood, and will reign over the universe to God's glory.

With Tamar it is her sin that stands out, as with Rahab it is her faith. For Ruth to come in, the sentence of the law has to be set aside. And Bathsheba shows us grace winning even over a believer's sin. A salvation for sinners. A salvation by faith. A salvation from the sentence of the law. An eternal salvation. This is what the simple placing of these names declares… Tamar's sin alone brought her into the Lord's genealogy, and God has taken pains to record, doubly record, this striking fact. In the same way, simply as sinners, we have the right to rejoice in a work done for the need of sinners.