But when ye shall see the abomination of desolation, spoken of by Daniel the prophet, standing where it ought not, (let him that readeth understand,) then let them that be in Judaea flee to the mountains:

But when ye see the abomination of desolation standing where he ought not (let him that readeth understand), then let them that are in Judaea flee unto the mountains:

And when you shall see the abomination of desolation, standing where it ought not: he that readeth let him understand: then let them that are in Judea, flee unto the mountains:

But when ye shall see the abomination of desolation standing where it should not, (he that reads let him consider it,) then let those in Judaea flee to the mountains;

But when you shall see the abomination of desolation, spoken of by Daniel the prophet, standing where it ought not, (let him that reads understand,) then let them that be in Judaea flee to the mountains:

"As soon, however, as you see the Abomination of Desolation standing where he ought not" - let the reader observe these words - "then let those in Judaea escape to the hills;

But when you see the unclean thing which makes destruction, in the place where it has no right to be (let this be clear to the reader), then let those who are in Judaea go quickly to the mountains:

Then, when you have seen the abomination of desolation, standing where it ought not to be, let the reader understand: then let those who are in Judea flee to the mountains.

"As soon, however, as you see 'the Foul Desecration' standing where it ought not" (the reader must consider what this means) "then those of you who are in Judea must take refuge in the mountains;

Let him that readeth understand - What he readeth, is added by D, and three of the Itala, perhaps needlessly.

But when ye shall see the abomination of desolation, spoken of by Daniel the prophet, (e) standing where it ought not, (let him that readeth understand,) then let them that be in Judaea flee to the mountains:
(e) When the heathen and profane people shall not only enter into the temple, and defile both it and the city, but also completely destroy it.

But when ye shall see the abomination of desolation,.... The Roman army encompassing Jerusalem, which was an abomination to the Jews, and an "impure sign" of their destruction, as the Syriac and Persic versions render it; and a desolating one to their nation, city, and temple:
spoken of by Daniel the prophet, in Daniel 9:27. This clause is omitted in the Vulgate Latin, and was not found by Beza, in two of his copies, and is thought to be transcribed from Matthew:
standing where it ought not; round about the city, in the midst of it, and even in the temple: in one of Beza's exemplars it is added, "in the holy place", as in Matthew; and so it is read in the Ethiopic version:
let him that readeth understand; either the passage in Daniel, or the citation of it by the evangelist, when he shall see this come to pass: this seems to be rather the words of the evangelist, than of Christ; since this was not written (and so not to be read), but spoken by Christ; and since his usual phrase was, "he that hath ears, let him hear": though indeed the same exhortation is in Matthew, and may be understood of Christ, as it may refer to the written prophecy in Daniel, and indeed to the Gospel, which might be read before this event came to pass: See Gill on Matthew 24:15.
Then let them that be in Judea flee to the mountains; they that are in Jerusalem, or in any of the cities and towns of Judea, let them make their escape, as soon as possible, to the mountainous parts of the country; where they may be more safe from, the devastations of the Roman army; See Gill on Matthew 24:16.

The Jews in rebelling against the Romans, and in persecuting the Christians, hastened their own ruin apace. Here we have a prediction of that ruin which came upon them within less than forty years after this. Such destruction and desolation, that the like cannot be found in any history. Promises of power to persevere, and cautions against falling away, well agree with each other. But the more we consider these things, the more we shall see abundant cause to flee without delay for refuge to Christ, and to renounce every earthly object, for the salvation of our souls.

But when ye shall see--"Jerusalem compassed by armies"--by encamped armies; in other words, when ye shall see it besieged, and
the abomination of desolation, spoken of by Daniel the prophet, standing where it ought not--that is, as explained in Matthew (Matthew 24:15), "standing in the holy place."
(let him that readeth understand)--readeth that prophecy. That "the abomination of desolation" here alluded to was intended to point to the Roman ensigns, as the symbols of an idolatrous, and so unclean pagan power, may be gathered by comparing what Luke says in the corresponding verse (Luke 21:20); and commentators are agreed on it. It is worthy of notice, as confirming this interpretation, that in 1 Maccabees 1:54--which, though aprocryphal Scripture, is authentic history--the expression of Daniel (Daniel 11:31; Daniel 12:11) is applied to the idolatrous profanation of the Jewish altar by Antiochus Epiphanes.
then let them that be in Judea flee to the mountains--The ecclesiastical historian, EUSEBIUS, early in the fourth century, tells us that the Christians fled to Pella, at the northern extremity of Perea, being "prophetically directed"--perhaps by some prophetic intimation more explicit than this, which would be their chart--and that thus they escaped the predicted calamities by which the nation was overwhelmed.

Where it ought not - That place being set apart for sacred use. Matthew 24:15; Luke 21:20; Daniel 9:27.