The exchangers - The "exchangers" were persons who were in the habit of borrowing money, or receiving it on deposit at a low rate of interest, to be loaned to others at higher interest. They commonly sat by "tables" in the temple, with money ready to exchange or loan. See Matthew 21:12. This money was left with the servant, not to exchange, nor to increase it by any such idle means, but by honest industry and merchandise; but since he was too indolent for that, he ought at least to have loaned it to the exchangers, that his master might have received some benefit from it.
With usury - With interest, increase, or gain. The word "usury," in our language, has a bad signification, meaning unlawful or exorbitant interest. This was contrary to the law, Exodus 22:25; Leviticus 25:36. The original means "gain," increase, or lawful interest.

With usury - Συν τοκω, with its produce - not usury; for that is unlawful interest, more than the money can properly produce.

Thou oughtest therefore to have put my money to the (e) exchangers, and [then] at my coming I should have received mine own with usury.
(e) Bankers who have their shops or tables set up abroad, where they lend money at interest. Usury or loaning money at interest is strictly forbidden by the Bible, (Exodus 22:25-27; Deuteronomy 23:19-20). Even a rate as low as one per cent interest was disallowed, (Nehemiah 5:11). This servant had already told two lies. First he said the master was an austere or harsh man. This is a lie for the Lord is merciful and gracious. Next he called his master a thief because he reaped where he did not sow. Finally the master said to him sarcastically why did you not add insult to injury and loan the money out at interest so you could call your master a "usurer" too! If the servant had done this, his master would have been responsible for his servant's actions and guilty of usury.

Thou oughtest therefore to have put my money to the exchangers,.... "Trapezites", or "tablets", the same whom the Jews (z) call and is the same word which is here used in Munster's Hebrew Gospel; who were so called from the table that stood before them, on which they told, and paid their money, and the exchange and use: hence all the Oriental versions here read, "thou shouldest have put my money to, or on the table"; put it into the hand of these bankers, where it would have been not only safe, as in the earth, where it was hid, but also would have made some increase, and would have been returned with profit,
and then at my coming I should have received my own with usury: this is said not so much to encourage usury, though it may be lawful; and it seems to have been a practice in those times to put money out to use upon a reasonable interest; but to reprove the sloth and inactivity of this servant, upon his own reasonings, and the character he had given of his master,
(z) Maimon. Hilch. Shekalim, c. 1. sect. 9. & c. 2. sect. 1.

thou oughtest therefore to have put my money to the exchangers--the banker.
and then at my coming I should have received mine own with usury--interest.

Thou oughtest to have put my money to the exchangers. To the bankers. If the lord was so exacting as he supposed, he ought at least to have put his money to use with the money brokers that it might have earned something.
Usury. Interest. The Jews were forbidden to take it from their brethren, but were allowed to take it from aliens.

Thou oughtest therefore - On that very account, on thy own supposition, to have improved my talent, as far as was possible.