Yahweh tells Moses to bring the elders of Israel to meet him on Mount Sinai. Moses has the Israelites make offerings. Moses and Joshua go onto the mountain and stay 40 days and 40 nights.
Exodus 16: Mana and Quail
The Israelites grumble that they have nothing to eat. Yahweh provides them quail at night and manna in the morning to make bread. As a test of their faith, Yahweh tells them to take only enough manna for one day; two days before the sabbath.