I rent my garment and my mantle. Rending the clothes was always, and still is, one of the commonest Oriental modes of showing grief. Reuben rent his clothes when his brothers sold Joseph to the Midianites, and Jacob did the same when he believed that Joseph was dead (Genesis 37:29, Genesis 37:34).
Job "rent his mantle" on learning the death of his sons and daughters (Job 1:20); and his friends "rent every one his mantle when they came to mourn with him and comfort him" (Job 2:11, Job 2:12). Rent clothes indicated that a messenger was a messenger of woe (1 Samuel 4:12; 2 Samuel 1:2), or that a man had heard something that had greatly shocked him, and of which he wished to express his horror (2 Kings 18:37; Matthew 26:65).
Ezra's action is of this last kind, expressive of horror more than of grief, but perhaps in some degree of grief also. And plucked off the hair of my head and of my beard. These are somewhat unusual signs of grief among the Orientals, who were wont to shave the head in great mourning, but seldom tore the hair out by the roots.
The practice is not elsewhere mentioned in Scripture, excepting in the apocryphal books (1 Esdras 8:71; 2 Esdras 1:8; Apoc. Esther 4:2). And sat down astonied. Compare Daniel 4:19; Daniel 8:27, where the same verb is used in the same sense.