Genesis 38:15

When Judah saw her, he thought her [to be] an harlot
By her posture and the place she was in: because she had covered her face;
with her veil, that he did not know her; for this is not given as a reason why he took her to be an harlot; the reason of this was, because she sat in the public road; but having covered her face he could not discern who she was, and therefore, from the other circumstance, concluded that she was an harlot, and sat there to prostitute herself to any that passed by.