Exodus 24:15-18

And Moses went up into the mount, and a cloud covered the mount. And the glory of the LORD abode upon mount Sinai, and the cloud covered it six days: and the seventh day he called unto Moses out of the midst of the cloud. And the sight of the glory of the LORD was like devouring fire on the top of the mount in the eyes of the children of Israel. And Moses went into the midst of the cloud, and gat him up into the mount: and Moses was in the mount forty days and forty nights.