Except these days should be shortened ( ἐκολοβω ìθησαν, had been shortened). In the midst of wrath God thinks on mercy. He providentially ordained that the days of vengeance should not be indefinitely prolonged; the siege was practically of short duration, the country was not wholly overrun and desolated.
The natural causes that combined to produce this shortening of the siege have been recounted by commentators. These were—the divided counsels of the Jews themselves, the voluntary surrender of parts of the fortifications, the fierce factions in the city, the destruction of magazines of provisions by calamitous fire, the suddenness of the arrival of Titus, and the fact that the walls had never been strengthened, as Herod Agrippa had intended.
There should no flesh be saved; i.e. the whole Jewish nation would have been annihilated. For the elect's sake. At the intercession of the escaped Christians, who offered up unceasing prayer for their brethren and countrymen, God lessened the duration of the calamities.
"The supplication of a righteous man availeth much in its working" (James 5:16). Ten righteous would have saved Sodom; Lot's intercession did preserve Zoar (comp. Isaiah 6:13; Jeremiah 5:1; Acts 27:24).
Some, not so suitably, explain "the elect" to be those Jews who should hereafter turn to the Lord; or the elect seed, "beloved for the fathers'sake" (Romans 11:28). We may well believe that the local tribulations, such as are intimated by Daniel and Christ, and their limitation in time, are a picture of what shall happen in the last days, the intermediate fulfilment being the prelude of the final accomplishment.