Deuteronomy 9:18 - Ellicott's Commentary On The Whole Bible

And I fell down before the Lord, as at the first, forty days and forty nights. — Moses had already interceded for them in Sinai before he came down on the fortieth day (Exodus 32:11-14). He now spent forty days and nights in the work of intercession. We are not to understand that the first forty were so spent. At that time he received the pattern of the tabernacle and the directions for the priesthood, which he did not deliver to Israel until after he descended from Sinai the second time. (See Exodus 24:18, and Exodus 35:1. &c.) During the first forty days, Joshua was with Moses in the mount (probably to help in taking the pattern for the tabernacle); during the second forty Moses was alone.