Genesis 38:6-16

Now Judah took a wife for Er his firstborn; her name was Tamar. But Er, Judah’s firstborn, was evil in the sight of the LORD, and the LORD killed him [in judgment]. Then Judah told Onan, “Go in to your brother’s widow, and perform your duty as a brother-in-law [under the levirate marriage custom]; [be her husband and] raise children for [the name of] your brother.” [Deut 25:5-10] Onan knew that the child (heir) would not be his [but his dead brother’s]; so whenever he lay with his brother’s widow, he spilled his seed on the ground [to prevent conception], so that he would not give a child to his brother. But what he did was displeasing in the sight of the LORD; therefore He killed him also [in judgment]. Then Judah said to Tamar, his daughter-in-law, “Remain a widow at your father’s house until Shelah my [youngest] son is grown”; [but he was deceiving her] for he thought that [if Shelah should marry her] he too might die like his brothers did. So Tamar went and lived in her father’s house. But quite a while later, Judah’s wife, the daughter of Shua, died; and when the time of mourning was ended, he went up to his sheepshearers at Timnah with his friend Hirah the Adullamite. Tamar was told, “Listen, your father-in-law is going up to Timnah to shear his sheep.” So she removed her widow’s clothes and covered herself with a veil, and wrapped herself up [in disguise], and sat in the gateway of Enaim, which is on the road to Timnah; for she saw that Shelah had grown up, and she had not been given to him as a wife [as Judah had promised]. When Judah saw her, he thought she was a [temple] prostitute, for she had covered her face [as such women did]. He turned to her by the road, and said, “Please come, let me lie with you”; for he did not know that she was his daughter-in-law. And she said, “What will you give me, that you may lie with me?”