After leaving Elim, the entire Israelite community set out into the wilderness of Sin, which lay between Elim and Sinai. This occurred on the fifteenth day of the second month after their departure from Egypt. There, in the wilderness, the whole community began to grumble against Moses and Aaron, complaining that it would have been better to have died in Egypt, where they at least had food to eat. They accused their leaders of bringing them into the desert only to starve the entire assembly to death.

The LORD heard their complaints and spoke to Moses, promising to rain down bread from heaven for the people. Each day the people were to go out and gather only enough for that day, as this would serve as a test of whether they would follow the LORD's instructions. On the sixth day, however, they were to gather twice the normal amount. Moses and Aaron then relayed the LORD's message to the people, reminding them that it was not against Moses and Aaron that they were grumbling, but against the LORD Himself. As Aaron spoke to the whole community, they looked toward the wilderness and saw the glory of the LORD appearing in a cloud.

That evening, quail came and covered the camp, providing the people with meat. In the morning, a layer of dew surrounded the camp. When it evaporated, thin flakes appeared, like frost on the ground. The people didn't know what it was and asked one another, "What is it?" — which in Hebrew is mān, the origin of the name "manna." Moses told them it was the bread the LORD had given them to eat. They were instructed to gather an omer per person. When they measured what they had collected, those who gathered much did not have too much, and those who gathered little did not have too little — each had exactly what they needed.

Moses warned the people not to keep any of it until morning, but some disobeyed and kept part of it overnight. By morning it was full of maggots and began to stink, and Moses was angry with them. Each morning the people gathered what they needed, and, as the sun grew hot, the manna melted away. On the sixth day they gathered twice as much — two omers per person — and the leaders of the community came to report this to Moses. Moses explained that the next day was a holy Sabbath rest unto the LORD, and that they should bake or boil whatever they wished that day, saving the rest for the Sabbath. When they set it aside until morning, it did not spoil or stink, as had happened on the other days. Moses told them to eat it that day because it was the Sabbath and none would be found on the ground.

Nevertheless, some of the people went out on the Sabbath to gather manna and found nothing. The LORD expressed his displeasure to Moses, asking how long the people would refuse to keep his commands and instructions. He reminded them that the Sabbath was given to them as a day of rest, and that on the sixth day they would always receive a double portion. So the people rested on the seventh day.

The Israelites called the bread "manna." It was white like coriander seed and tasted like wafers made with honey. Moses, following the LORD's instructions, directed Aaron to take an omer of manna and place it before the LORD as something to be kept for future generations so that they would be able to see the bread the LORD had provided in the wilderness. Aaron placed it before the Testimony, where it was preserved as God had commanded Moses. The Israelites ate manna for forty years, continuing to do so until they reached the border of Canaan.