This refers to the practice of taking a garment as security for a loan. Normally only unnecessary garments could be taken from a debtor and they had to be returned (i.e., they could not be kept overnight). The Israelites were thus breaking biblical law and exploiting those who are poor (Exodus 22:26–27).
8 they lay themselves down beside every altar on garments taken in pledge, and in the house of their God they drink the wine of those who have been fined.