Exodus 3:1

3:1 Now Moses was shepherding the flock of his father-in-law Jethro, the priest of Midian, and he led the flock to the far side of the desert and came to the mountain of God, to Horeb.

Exodus 19:3

19:3 Moses went up to God, and the Lord called to him from the mountain, “Thus you will tell the house of Jacob, and declare to the people of Israel:

Exodus 24:17-18

24:17 Now the appearance of the glory of the Lord was like a devouring fire on the top of the mountain in plain view of the people. 24:18 Moses went into the cloud when he went up the mountain, and Moses was on the mountain forty days and forty nights.