Exodus 24:16-18

16The Lord's bright glory appeared on Sinai mountain. The cloud covered the mountain for six days. On the seventh day, the Lord called out to Moses from inside the cloud.

17The people could see the Lord's bright glory. To them, it looked like a fire that was burning the top of the mountain.

18Moses went up the mountain and he went into the cloud. He stayed on the mountain for 40 days and 40 nights.