Albert Barnes Commentary Job 33:18

"He keepeth back his soul from the pit, And his life from perishing by the sword." — Job 33:18 (ASV)

He keeps back his soul from the pit - The word "soul" in Hebrew is often equivalent to "self," and the idea is that God keeps a person from the pit in this manner.

The object of these warnings is to prevent such a person from rushing into their own destruction.

The word rendered “pit”—שׁחת shachath—properly means a pit or pitfall in which traps are laid for wild animals (Psalms 7:15; Psalms 9:15).

It can also mean a miry cistern (Job 9:31), a prison (Isaiah 51:14), or the grave or sepulchre, often being a cavern (Job 17:13; Psalms 30:9; see Job 33:28, Job 33:30).

In this context, “pit” evidently means the grave. The sense is that God thus warns people against pursuing a course of conduct that would lead them to destruction or would speedily terminate their lives.

And his life from perishing by the sword - The margin reads, “passing by.” The meaning of the Hebrew may be “to keep his life from passing away by the sword,” as if the sword were the means by which life, or the soul, passed from the body.

The word rendered “sword” here—שׁלח shelach—is from שׁלח shâlach, meaning to send, cast, or hurl. The reference is therefore more likely to something sent, such as an arrow, dart, or javelin, than to a sword.

The overall sense is not materially varied, and the idea referred to is that of a violent death. The meaning is that God, by these warnings, would keep a person from such a course of life as would lead to a death by violence—either by punishment for their crime or by being cut off in war.