John Gill Commentary Mark 13:26

"And then shall they see the Son of man coming in clouds with great power and glory." — Mark 13:26 (ASV)

And then shall they see the son of man
Not in person, but in the power of his wrath and vengeance; of which the Jews then had a convincing evidence, and full proof; and even of his being come in the flesh, as if they had seen him in person: this shows, that the sign of the son of man, in (Matthew 24:30) is the same with the son of man:

coming in the clouds with great power and glory;
not to judgment, but having taken vengeance on the Jewish nation, to set up his kingdom and glory in the Gentile world; (See Gill on Matthew 24:30).