Deuteronomy 10:3

And I made an ark of shittim wood, and hewed two tables of stone like unto the first, and went up into the mount, having the two tables in mine hand.

I made an ark of shittim wood. It appears, however, from Exodus 37:1, that the ark was not framed until his return from the mount; or, most probably, he gave instructions to Bezeleel, the artist employed on the work, before he ascended the mount, that on his descent it might be finished, and ready to receive the precious deposit.