Lessons from Exodus

I'm following one of those Bible reading plans this year and I'm nearing the end of Exodus. I had an interesting thought I thought might be worth while sharing. It's rather undeveloped, so be kind in your criticism. :)

In Exodus 36 (vv.2-7) the people of Isreal donate their silver and gold to the Lord in having the Ark, Tabernacle and other requirements for worship constructed. According to the text there was so much they had to stop; they were actually "restrained from giving for the material they had was sufficient to do all the work, and more." But... where does an impoverished 400 year old slave nation get that kind of wealth?