In the third month after leaving Egypt, Israel camped before Sinai. The LORD called them His treasured possession and a kingdom of priests, then descended on the mountain in fire, thunder, lightning, cloud, and trumpet sound (Exodus 19:1-25), 1491 BC.
genealogical dating
📖 Exodus 19:1–3
1In the third month, on the same day of the month that the Israelites had left the land of Egypt, they came to the Wilderness of Sinai. 2After they had set out from Rephidim, they entered the Wilderness of Sinai, and Israel camped there in front of the mountain. 3Then Moses went up to God, and the LORD called to him from the mountain, “This is what you are to tell the house of Jacob and explain to the sons of Israel:
Hebrews recalls Israel's fearful approach to Mount Sinai and quotes the command that even an animal touching the mountain was to be stoned.
Hebrews 12:18–20
For you have not come to a mountain that can be touched and that is burning with fire; to darkness, gloom, and storm; to a trumpet blast or to a voice that made its hearers beg that no further word be spoken. For they could not bear what was commanded: “If even an animal touches the mountain, it must be stoned.”
Exodus 19:12-13 commands Israel to remain outside the mountain's boundary and says that any person or animal touching it must die; Hebrews 12:18-21 recalls the fire, darkness, trumpet, and fear at Sinai and quotes the command concerning an animal.
