Albert Barnes Commentary Job 30:21

"Thou art turned to be cruel to me; With the might of thy hand thou persecutest me." — Job 30:21 (ASV)

Thou art become cruel to me — Margin, "turned to be." This language, applied to God, seems harsh and irreverent, and one may well ask whether the word "cruel" does not express an idea Job did not intend. The Hebrew word אכזר 'akzâr — is from an obsolete root כזר — not found in Hebrew. The Arabic root, nearly the same as this, means to break with violence, to rout as an enemy, and then to be enraged. In Syriac, the primary idea is that of a soldier, and from there it may refer to such acts of violence as a soldier commonly commits.

The word occurs in Hebrew in the following places and is translated in the following manner: It is rendered “cruel” in Deuteronomy 32:33; Job 30:21; Proverbs 5:9; Proverbs 11:17; Proverbs 12:10; Proverbs 17:11; Proverbs 27:4; Isaiah 13:9; Jeremiah 6:23; Jeremiah 50:42; Jeremiah 30:14; and “fierce” in Job 41:10.

Jerome renders it, mutatus mihi in crudelem — “you are changed so as to become cruel to me;” the Septuagint renders it, ἀνελεημόως aneleēmonōs — unmerciful; Luther, Du bist mir verwandelt in einem Grausamen — “you are changed to me into a cruel one;” and so Umbreit, Noyes, and translators generally. Perhaps the word "fierce," "severe," or "harsh" would express the idea; still, it must be admitted that Job, in the severity of his sufferings, is often betrayed into language that cannot be a model for us and that we cannot vindicate.

With thy strong hand — Margin, "the strength." So the Hebrew. The hand is the instrument by which we accomplish anything; therefore, anything that God does is traced to His hand.

Thou opposest thyself against me — תשׂטמני tiśâṭamēniy. The word שׂטם śâṭam — means to lie in wait for anyone, to lay snares, or to set a trap; see Job 16:9, where the same word occurs, and where it is rendered “who hateth me,” but where it would be better rendered “he pursues me” or “persecutes me.” The meaning is that God had become His adversary, or had set Himself against him. There was a severity in His dealings with him as if He had become a foe.