“But when the Son of man shall come in his glory, and all the angels with him, then shall he sit on the throne of his glory,”
Significantly here the Son of Man is paralleled with the King (Matthew 25:32). In Daniel 7:13-14 the son of man came into the presence of the Ancient of Days and was given a kingdom and glory and dominion. In the case of Jesus this was fulfilled by His enthronement after the resurrection (Matthew 28:18; Acts 2:36; Acts 7:55-56) when He received His eternal kingdom (Daniel 7:14). And now that glory is to be openly revealed to the world. Compare Matthew 16:27 where the Son of Man comes in the glory of His Father with His angels in order to render to every man according to his deeds, and Matthew 24:30-31 where the Son of Man comes on the clouds of Heaven with power and great glory and sends out His angels to gather His elect. Both are being fulfilled here. The angels are attendants who carry out the duties required by the court. That the Son of Man is Jesus is demonstrated by the fact that it is the answer to the question about ‘Your coming' (Matthew 24:3), and this is confirmed by the use of the term Son of Man throughout the remainder of the Gospel. One significance of the title Son of Man was that Jesus was bringing out that His life was finally fulfilling Old Testament prophecy.
‘Then shall He sit on the throne of his glory.' As He will have been given a kingdom, and glory and dominion (Daniel 7:14), He will clearly have received His throne. This is thus that very throne where He received His glory. But regularly it is also His Father's throne (Revelation 5:6; Revelation 6:16-17; Revelation 14:14; Daniel 7:13-14; Jeremiah 14:21) where He sits at His right hand (Psalms 110:1; Acts 2:34; Acts 7:55-56; Romans 8:34; Ephesians 1:20; Colossians 3:1; Hebrews 1:3; Hebrews 1:13; Hebrews 8:1; Hebrews 10:12; Hebrews 12:2; 1 Peter 3:22), and from which the covenant is confirmed and made sure (Jeremiah 14:21). Isaiah had seen it in vision (Isaiah 6:1). It was the place from which judgments were made. Here Jesus is making clear that He is, as the Son of Man, the Judge of all the earth (compare John 5:22; John 5:27; Genesis 18:25).