Albert Barnes 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)

Grant that these my two sons may sit, etc. They were still looking for a temporal kingdom. They expected that he would reign on the earth with great pomp and glory. They expected that he would conquer as a prince and a warrior. They wished to be distinguished in the day of his triumph.

To sit on the right and left hand of a prince was a token of confidence, and the highest honour granted to his friends (1 Kings 2:19; Psalms 110:1; 1 Samuel 20:25).

The disciples here had no reference to the kingdom of heaven, but only to the kingdom which they supposed he was about to set up on the earth.