At that time the Lord said unto me, Hew thee two tables of stone like unto the first, and come up unto me into the mount, and make thee an ark of wood. (Deuteronomy 10:1)
That is, the 40 days and nights of intercession spoken of in ch. 9, which followed this command (Ex. 34:1, 2, 28).
Hew thee.
The first stone tables were provided by God (Ex. 24:12), the second by Moses.
Make thee an ark.
This command was given during the first period of 40 days (Ex. 25:10). Some Jewish commentators havemaintained that there were two arks, one to go before the people in their warfare and another to remain in the tabernacle, but of this there is no evidence whatever. The ark here referred to can be no other than the ark, for now, 38 years later, the tables were still where Moses first placed them (v. 5).