Albert Barnes Commentary Matthew 16:27

"For the Son of man shall come in the glory of his Father with his angels; and then shall he render unto every man according to his deeds." — Matthew 16:27 (ASV)

For the Son of man, and so on. This means the Lord Jesus Christ will return to judge the world. He will come in glory—the glory of his Father—the majesty with which God is accustomed to appear, and which befits God. He will be attended by angels. He will judge all people.

Reward. The word reward means recompense, or the rendering of justice. He will deal with them according to their character. The righteous he will reward in heaven, with glory and happiness. The wicked he will send to hell, as a reward or recompense for their evil works. This fact, that he will come to judgment, he gives as a reason why we should be willing to deny ourselves and follow him. Even though now it may be attended with contempt and suffering, yet then he will reward his followers for all their shame and sorrows, and receive them to his kingdom. He adds, Mark 8:38, that if we are ashamed of him here, he will be ashamed of us there. That is, if we reject and disown him here, he will reject and disown us there.

And then: see Revelation 22:12.