Make covenant with the Lord

Exodus 24:1-18
The 70 elders and Moses, Aaron, Nadab and Abihu made covenant with the Lord, they said "We will do everything the Lord has said; we will obey."
They saw  the God of Israel. Under his feet was something like a pavement made of sapphire, clear as the sky itself.
The people's assent to the covenant is formally sealed by a special sacrifice, and by the covenant meal eaten by their representatives in the presence of God.
The blood sprinkled on the people and on the altar unites the two parties to the agreement. In effect, each is swearing to keep it on pain of death.
Nadab and Abihu: Two of Aaron's sons who later died, disgraced.
They saw the God of Israel: Having a meal with someone is the essence of fellowship in the Near East. The writer is almost lost for words to describe the indescribable communion which followed the sacrifice and fulfilled the covenant.
Hur: Obvious a man of standing in Israel. He and Aaron help up Moses' hands in prayer during the battle with the Amalekites.
Forty days and nights: Certain numbers have special significance in the Bible. The round number 40 occurs at almost every new stage in Israel's history: e.f. at the flood, the time of the spies in Canaan, Elijah's journey to Horeb, Jesus' time in the wilderness, and the time between his resurrection and ascension.
How?
God is Holy and fulfill with glory and honor above all!