Let no man leave of it till the morning - For God would have them to take no thought for the morrow, and constantly to depend on him for their dally bread. And is not that petition in our Lord's prayer founded on this very circumstance, Give us day by day our daily bread?

And Moses said unto them,.... At the same time he gave the direction to them about gathering it, and measuring out to every man an omer:

let no man leave of it until the morning; not that every man was bound to eat up the quantity distributed to him; he might give what he could not eat to those that could eat more, if there were any such; or he might give it to his cattle, or cast it away, but he was not to reserve it until the next day for his use; which was to teach him that God would bestow this benefit and blessing on him daily, and he might expect it, whose mercies are new every morning; and to instruct him to live every day upon the providence of God for his daily food; as indeed every man ought to do so, let his circumstances be ever so affluent; and, in a more spiritual and evangelic sense, it teaches believers to live continually every day by faith on Christ, and to say day by day, Lord, evermore give us this bread, John 6:34.

In the second place, Moses commanded them, that no one was to leave any of what had been gathered till the next morning. Some of them disobeyed, but what was left went into worms (תּולעים ירם literally rose into worms) and stank. Israel was to take no care for the morrow (Matthew 6:34), but to enjoy the daily bread received from God in obedience to the giver. The gathering was to take place in the morning (Exodus 16:21); for when the sun shone brightly, it melted away.

And Moses said, Let no man leave of it till the morning.

16:19 Let no man leave 'till morning - But let them learn to go to bed and sleep quietly, though they had not a bit of bread in their tent, nor in all their camp, trusting God with the following day to bring them their daily bread. Never was there such a market of provisions as this, where so many hundred thousand men were daily furnished without money, and without price: never was there such an open house kept as God kept in the wilderness for 40 years together, nor such free and plentiful entertainment given. And the same wisdom, power and goodness that now brought food daily out of the clouds, doth in the constant course of nature bring food yearly out of the earth, and gives us all things richly to enjoy.

16:13-21 At evening the quails came up, and the people caught with ease as many as they needed. The manna came down in dew. They called it Manna, Manhu, which means, What is this? It is a portion; it is that which our God has allotted us, and we will take it, and be thankful. It was pleasant food; it was wholesome food. The manna was rained from heaven; it appeared, when the dew was gone, as a small round thing, as small as the hoar frost, like coriander seed, in colour like pearls. The manna fell only six days in the week, and in double quantity on the sixth day; it bred worms and became offensive if kept more than one day, excepting on the sabbath. The people had never seen it before. It could be ground in a mill, or beaten in a mortar, and was then made into cakes and baked. It continued the forty years the Israelites were in the wilderness, wherever they went, and ceased when they arrived in Canaan. All this shows how different it was from any thing found before, or found now. They were to gather the manna every morning. We are hereby taught, 1. To be prudent and diligent in providing food for ourselves and our households; with quietness working, and eating our own bread, not the bread of idleness or deceit. God's bounty leaves room for man's duty; it did so even when manna was rained; they must not eat till they have gathered. 2. To be content with enough. Those that have most, have for themselves but food and raiment; those that have least, generally have these; so that he who gathers much has nothing over, and he who gathers little has no lack. There is not such a disproportion between one and another in the enjoyment of the things of this life, as in the mere possession of them. 3. To depend upon Providence: let them sleep quietly, though they have no bread in their tents, nor in all their camp, trusting that God, with the following day, would bring them in their daily bread. It was surer and safer in God's storehouse than their own, and would come thence sweeter and fresher. See here the folly of hoarding. The manna laid up by some, who thought themselves wiser, and better managers, than their neighbours, and who would provide lest it should fail next day, bred worms, and became good for nothing. That will prove to be most wasted, which is covetously and distrustfully spared. Such riches are corrupted, Jas 5:2,3. The same wisdom, power, and goodness that brought food daily from above for the Israelites in the wilderness, brings food yearly out of the earth in the constant course of nature, and gives us all things richly to enjoy.