Albert Barnes Commentary Malachi 3:10

"Bring ye the whole tithe into the store-house, that there may be food in my house, and prove me now herewith, saith Jehovah of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough [to receive it]." — Malachi 3:10 (ASV)

Bring the whole tithes - not a part only, keeping back more or less, and, as he had said, defrauding God, offering, like Ananias, a part as if it had been the whole. Bring them into the treasury, where they were collected in the time of Hezekiah and again at this time by the direction of Nehemiah, so that there shall be food—not superfluity—in My house for those who minister in the house of My sanctuary (Nehemiah 13:10–23).

Before the reformation, the Levites and singers had fled, every one to his field, because the portion of the Levites had not been given them. On Nehemiah’s remonstrance, aided by Malachi, the tithe of corn and the wine and the new oil were brought into the treasuries.

Bring the whole tithes - "You know that all things which come to you are God’s, and do you not give of His own to the Creator of all? The Lord God does not need anything; He asks not for a reward, but reverence. He asks not for anything of yours to restore to Him. He asks of you 'first-fruits and tithes.'

"Stingy one, what would you do if He took nine parts to Himself and left you the tenth? What if He said to you: ‘Man, you are Mine, Who made you. Mine is the land which you till; Mine are the seeds which you sow; Mine are the animals which you work; Mine are the showers, Mine the winds, Mine the sun’s heat. And since Mine are all the elements by which you live, you who give only the labor of your hands deserve only the tithes.’

"But since Almighty God lovingly feeds us, He gives a most ample reward to us who labor little. Claiming to Himself the tithes only, He has remitted to us all the rest."

And prove Me now with this, in or by this thing - God pledges Himself to His creatures in a way that they themselves can verify. "If you will obey, I will supply all your needs; if not, I will continue your dearth." By whatever laws God orders the material creation, He gave them a test; they themselves could judge its completion—indeed, they must have judged it. They had been afflicted with years of want. God promises them years of plenty on a condition which He names. What would people think now if anyone had, in God’s name, promised that such and such a disease which injured our crops or our cattle should come at once to an end if any one of God’s laws should be kept? We would have been considered fanatics, and rightly so, for we had no commission from God.

God authenticates those by whom He speaks; He promises, who alone can perform.

"There are three keys which God has reserved in His own hands and has not delivered to any minister or substitute: the keys of life, of rain, and of the resurrection. In the ordering of the rain, people behold His great power, no less than in giving life at first or afterward raising the dead to it. As Paul says (Acts 14:17), God left not Himself without witness, in that He did good and gave rain, from heaven and fruitful seasons."

If I will not open the windows of heaven - In the time of the flood, they were, as it were, opened to humanity’s destruction; now, God would rain abundantly for you, for their sakes. And pour you out—literally empty out to you—giving to you fully, holding back nothing. So in the Gospel it is said that the love of God is shed abroad, poured out and forth, in our hearts by the Holy Spirit who is given to us.

That there is not room enough to receive it—literally, "until there is no sufficiency." (In Psalms 72:7 (quoted by Gesenius, Rosenmüller, etc.), there shall be abundance of peace ירח בלי עד—literally, “until there be no moon”—has a literal meaning: that the peace should last until the end of our creation, without saying anything of what lies beyond.) The text does not express what should not suffice, whether on God’s part or on man’s. Yet it would be too great an irony if understood of God.

His superabundance, above all which we can ask or think, is a first principle in the conception of God as the Infinite Source of all being. But to say of God that He would pour out His blessing until humans could not contain it is one bliss of eternity: that God’s gifts will overflow the capacity of His creatures to receive them. The pot of oil poured forth the oil until, on the prophet’s saying (2 Kings 4:6), Bring me yet a vessel, the widow’s son said, There is not a vessel more. And the oil stayed. God’s gifts are limited only by our capacity to receive them.