John Calvin Commentary Matthew 20:21

"And he said unto her, What wouldest thou? She saith unto him, Command that these my two sons may sit, one on thy right hand, and one on thy left hand, in thy kingdom." — Matthew 20:21 (ASV)

In the kingdom. It was commendable in the sons of Zebedee that they expected some kingdom of Christ, of which not even the slightest trace was then visible. They saw Christ exposed to contempt in the humble form of a servant; indeed, they saw him despised and loaded with many reproaches by the world. Yet, they were convinced that he would soon become a magnificent king, for he had taught them so.

This is unquestionably a noble example of faith. But from this we see how easily the pure seed, as soon as it is implanted in our hearts, becomes degenerate and corrupted. For they imagined a kingdom that did not exist and then immediately fell into the folly of desiring the highest places.

Therefore, since this wicked ambition stemmed from a general principle of faith—which in itself was highly commendable—we should pray not only that the Lord would open the eyes of our minds, but also that he would give us continual guidance and keep our minds fixed on the proper object. We should also pray not only that he would grant us faith, but also that he would keep it pure from all adulteration.