Genesis 38:11

7Er, Judah’s firstborn, was wicked in the LORD’s sight. So the LORD killed him.

8Judah said to Onan, “Go in to your brother’s wife, and perform the duty of a husband’s brother to her, and raise up offspring for your brother.”

9Onan knew that the offspring wouldn’t be his; and when he went in to his brother’s wife, he spilled his semen on the ground, lest he should give offspring to his brother.

10The thing which he did was evil in the LORD’s sight, and he killed him also.

11Then Judah said to Tamar, his daughter-in-law, “Remain a widow in your father’s house, until Shelah, my son, is grown up;” for he said, “Lest he also die, like his brothers.” Tamar went and lived in her father’s house.

12After many days, Shua’s daughter, the wife of Judah, died. Judah was comforted, and went up to his sheep shearers to Timnah, he and his friend Hirah, the Adullamite.

13Tamar was told, “Behold, your father-in-law is going up to Timnah to shear his sheep.”

14She took off the garments of her widowhood, and covered herself with her veil, and wrapped herself, and sat in the gate of Enaim, which is on the way to Timnah; for she saw that Shelah was grown up, and she wasn’t given to him as a wife.

15When Judah saw her, he thought that she was a prostitute, for she had covered her face.