Albert Barnes on Matthew 25:26

Slothful. Indolent, lazy, who had done nothing. God will judge men, not merely for doing wrong, but for not doing right. See Mt 25:45. That servant was wicked, because he had such an opinion of his master; he had shown that he was slothful, by not making good use of the talent, Mt 25:27.

Thou knewest, etc. This should be understood, and might have been translated, as a question. If you knew he was such a man, you ought to have acted accordingly, so as to have escaped punishment. "Didst thou know that I reap, etc? Then thou shouldst have given my money to the exchangers," etc. This is not intended to admit that he was such a man, but to convict the slothful servant of guilt and folly in not having been prepared to meet him.

(r) "wicked and slothful" Job 15:5,6, Mt 18:32, Lk 19:22, Jude 1:15