And Tamar put ashes on her head, and rent her garment of divers colors that was on her, and laid her hand on her head, and went on crying.

Wesley's Notes

13:19 Put ashes - To signify her grief for some calamity which had befallen her, and what that was, concurring circumstances easily discovered. Head - In token of grief and shame, as if she were unable and ashamed to shew her face. Crying - To manifest her abhorrency of the fact, and that it was not done by her consent.

Jamieson-Fausset-Brown Bible Commentary

19, 20. Tamar put ashes on her head, and rent her garment of divers colours . laid her hand on her head, and went on crying-that is, sobbing. Oriental manners would probably see nothing beyond a strong sense of the injury she had sustained, if Tamar actually rent her garments. But, as her veil is not mentioned, it is probable that Amnon had turned her out of doors without it, and she raised her hand with the design to conceal her face. By these signs, especially the rending of her distinguishing robe, Absalom at once conjectured what had taken place. Recommending her to be silent about it and not publish her own and her family's dishonor, he gave no inkling of his angry feelings to Amnon. But all the while he was in secret "nursing his wrath to keep it warm," and only "biding his time" to avenge his sister's wrongs, and by the removal of the heir-apparent perhaps further also his ambitious designs.

Matthew Henry's Concise Commentary

13:1-20 From henceforward David was followed with one trouble after another. Adultery and murder were David's sins, the like sins among his children were the beginnings of his punishment: he was too indulgent to his children. Thus David might trace the sins of his children to his own misconduct, which must have made the anguish of the chastisement worse. Let no one ever expect good treatment from those who are capable of attempting their seduction; but it is better to suffer the greatest wrong than to commit the least sin.