Albert Barnes Commentary Matthew 25:21

"His lord said unto him, Well done, good and faithful servant: thou hast been faithful over a few things, I will set thee over many things; enter thou into the joy of thy lord." — Matthew 25:21 (ASV)

Ruler over many things. I will promote you to greater honors and more important trusts.

Joy of your lord. In the meantime, share the pleasures and enjoyments of his palace, be his companion, and receive the rewards which he has promised you. The joy of his lord may mean either the festivals and rejoicing at his return or the rewards which his lord had prepared for his faithful servants.

Applied to Christians, this means that those who rightly improve their talents will, at the return of Christ, be promoted to great honors in heaven and will share in the joys of their Lord in the world of glory. (1 John 2:28).