John Gill Commentary Mark 13:29

"even so ye also, when ye see these things coming to pass, know ye that he is nigh, [even] at the doors." — Mark 13:29 (ASV)

So you, in like manner This is an accommodation of the parable to the present case:

when you shall see these things come to pass ; the signs preceding the destruction of Jerusalem, and especially the abomination of desolation, or the Roman army surrounding it:

know that it, or he is nigh, even at the doors ; either that the destruction of Jerusalem is near; or that the son of man is just ready to come to take vengeance on it; or as Luke says, (Luke 21:31) , the kingdom of God is nigh at hand; or a more glorious display of the kingly power of Christ, in the destruction of his enemies, and a greater spread of his Gospel in the Gentile world; (See Gill on Matthew 24:33).