Exodus 24:13-18

So Moses and his helper Joshua set out, and Moses went up to Sinai, the mountain of God. Moses said to the elders, “Wait here for us until we come back to you. Aaron and Hur are with you, and anyone who has a disagreement with others can take it to them.” When Moses went up on the mountain, the cloud covered it. The glory of the LORD came down on Mount Sinai, and the cloud covered it for six days. On the seventh day the LORD called to Moses from inside the cloud. To the Israelites the glory of the LORD looked like a fire burning on top of the mountain. Then Moses went into the cloud and went higher up the mountain. He was on the mountain for forty days and forty nights.