Exodus 24:15-18

Moses went up on the mountain, and the cloud covered the mountain. Yahweh’s glory settled on Mount Sinai, and the cloud covered it six days. The seventh day he called to Moses out of the middle of the cloud. The appearance of Yahweh’s glory was like devouring fire on the top of the mountain in the eyes of the children of Israel. Moses entered into the middle of the cloud, and went up on the mountain; and Moses was on the mountain forty days and forty nights.