Arab means to become a pledge or surety for another — to put oneself at risk as a guarantor for someone else's debt or obligation. It appears about 22 times in various conjugations. Judah's offer to be surety for Benjamin (Genesis 43:9) and Boaz's role as kinsman-redeemer both echo this concept of one person standing in for another.
The act of becoming arab — a guarantor — has profound Christological resonance. Hebrews 7:22 explicitly calls Jesus the 'guarantee [engyos]' of a better covenant, making His role the NT fulfillment of the OT arab principle. Job desperately asks God to be his own surety (Job 17:3), a plea for God to guarantee Job's vindication. In Proverbs, becoming surety for a stranger is warned against — the danger of being trapped by one's pledge. Theologically, the entire sacrificial system worked on the principle that an innocent party (the animal, and ultimately Christ) became the arab — the pledge — absorbing the consequences for another's failure.