Genesis 38:13-16

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

14So she removed her widow’s clothes and covered herself with a veil. She wrapped herself and sat at the entrance to Enaim which is on the way to Timnah. (She did this because she saw that she had not been given to Shelah as a wife, even though he had now grown up.)

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

16He turned aside to her along the road and said, “Come on! I want to have sex with you.” (He did not realize it was his daughter-in-law.) She asked, “What will you give me in exchange for having sex with you?”