Exodus 24:16

A cloud covered the mount six days — A visible token of God's special presence there, for he so shews himself to us, as at the same time to conceal himself from us, he lets us know so much as to assure us of his power and grace, but intimates to us that we cannot find him out to perfection. During these six days Moses staid waiting upon the mountain, for a call into the presence — chamber. And on the seventh day — Probably the sabbath — day, he called unto Moses. Now the thick cloud opened in the sight of all Israel, and the glory of the Lord broke forth like devouring fire.