Adam Clarke on Isaiah 1:4

Ah sinful nation "Degenerate" - Five MSS., one of them ancient, read משחתים moschathim, without the first י yod, in hophal corrupted, not corrupters. See the same word in the same form, and in the same sense, Pro 25:26.

Are corrupters "Are estranged" - Thirty-two MSS., five ancient, and two editions, read נזורו nazoru; which reading determines the word to be from the root זור zur, to alienate, not from נזר nazar, to separate; so Kimchi understands it. See also Annotat. in Noldium, 68.

They are gone away backward "They have turned their backs upon him" - So Kimchi explains it:" they have turned unto him the back and not the face." See Jer 2:27; Jer 7:24. I have been forced to render this line paraphrastically; as the verbal translation, "they are estranged backward," would have been unintelligible.