Thought her to be a harlot - See the original of this term, Genesis 34:31 (note). The Hebrew is זונה zonah, and signifies generally a person who prostitutes herself to the public for hire, or one who lives by the public; and hence very likely applied to a publican, a tavern-keeper, or hostess, Joshua 2:1; translated by the Septuagint, and in the New Testament, πορνη, from περναω, to sell, which certainly may as well apply to her goods as to her person.

It appears that in very ancient times there were public persons of this description; and they generally veiled themselves, sat in public places by the highway side, and received certain hire. Though adultery was reputed a very flagrant crime, yet this public prostitution was not; for persons whose characters were on the whole morally good had connections with them. But what could be expected from an age in which there was no written Divine revelation, and consequently the bounds of right and wrong were not sufficiently ascertained? This defect was supplied in a considerable measure by the law and the prophets, and now completely by the Gospel of Christ.

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.

When Judah saw her here and took her for a harlot, he made her an offer, and gave her his signet-ring, with the band (פּתיל) by which it was hung round his neck, and his staff, as a pledge of the young buck-goat which he offered her. They were both objects of value, and were regarded as ornaments in the East, as Herodotus (i. 195) has shown with regard to the Babylonians (see my Bibl. Arch. 2, 48). He then lay with her, and she became pregnant by him.

When Judah saw her, he thought her to be an harlot; because she had covered her face.

38:1-30 The profligate conduct of Judah and his family. - This chapter gives an account of Judah and his family, and such an account it is, that it seems a wonder that of all Jacob's sons, our Lord should spring out of Judah, Heb 7:14. But God will show that his choice is of grace and not of merit, and that Christ came into the world to save sinners, even the chief. Also, that the worthiness of Christ is of himself, and not from his ancestors. How little reason had the Jews, who were so called from this Judah, to boast as they did, Joh 8:41. What awful examples the Lord proclaims in his punishments, of his utter displeasure at sin! Let us seek grace from God to avoid every appearance of sin. And let that state of humbleness to which Jesus submitted, when he came to put away sin by the sacrifice of himself, in appointing such characters as those here recorded, to be his ancestors, endear the Redeemer to our hearts.