The Israelites entered Egypt with wealth of Abraham, etc. They lived for some time in the choicest lands of Egypt. There was the favor and substance of Joseph, etc. But somewhere in the transition into slavery they lost all of that. This is a picture of a child of God backsliding into the World, and loosing, among other things, his substance. (just like what happened to Lot when he entered Sodom)
But, when slavery was over God told them to "borrow" jewels, etc. from the Egyptians. They were getting some far overdue back pay. Some say they didn't borrow enough, because they ran out of substance not too long after. Whatever the case, the principal comes up. If we do not ask, we do not get.
The point of this message is to encourage us to ask, so that
Exodus 3:19-21 you shall not go empty