Genesis 38:14-15

14Tamar knew that Judah's son Shelah had now become a man. But Judah had not yet let Shelah marry her. So Tamar took off her widow's clothes and she put on other clothes. She covered her head with a veil. She did not want anyone to recognize her. Then she sat at the gate of Enaim. Enaim is a town on the road that goes to Timnah.

15Judah saw her as she sat there. He thought that she was a prostitute, because she had covered her face.