'Pledges' in the Bible

Most certainly [Lord] You have abandoned your people, the house of Jacob,Because they are filled with influences from the east,And they are soothsayers [who foretell] like the Philistines;Also they strike bargains with the children of foreigners (pagans).

Now therefore give pledges, I pray thee, to my master the king of Assyria, and I will give thee two thousand horses, if thou be able on thy part to set riders upon them.