Exodus 16:2-7, 32-33

The whole congregation of the Israelites [grew discontented and] murmured and rebelled against Moses and Aaron in the wilderness, and the Israelites said to them, “Would that we had died by the hand of the LORD in the land of Egypt, when we sat by the pots of meat and ate bread until we were full; for you have brought us out into this wilderness to kill this entire assembly with hunger.” Then the LORD said to Moses, “Behold, I will cause bread to rain from heaven for you; the people shall go out and gather a day’s portion every day, so that I may test them [to determine] whether or not they will walk [obediently] in My instruction (law). And it shall be that on the sixth day, they shall prepare to bring in twice as much as they gather daily [so that they will not need to gather on the seventh day].” So Moses and Aaron said to all Israel, “At evening you shall know that the LORD has brought you out of the land of Egypt, and in the morning you will see the glory of the LORD, for He hears your murmurings against the LORD. What are we, that you murmur and rebel against us?”

Then Moses said, “This is the word which the LORD commands, ‘Let an omer of it be kept throughout your generations, that they may see the bread with which I fed you in the wilderness, when I brought you out of the land of Egypt.’ ” So Moses said to Aaron, “Take a pot and put an omer of manna in it, and place it before the LORD to be kept throughout your generations.”