What is the purpose of a pledge?
Answer From The Annual Reading Schedule - Week 47 Notes For Deuteronomy: When someone was poor and needs to borrow food or silver or whatever from their brother, they would give an item of value of theirs as a pledge to show their sincerity in paying back the brother they are borrowing from. In general, a pledge is something given to show the seriousness and the certainty of payment to come.