Jerome

For the Lord knoweth them that are his, (2 Tim. 2:19.) and he that knoweth not shall not be known, and though they be virgins in purity of body, or in confession of the true faith, yet forasmuch as they have no oil, they are unknown by the bridegroom. When He adds, Watch therefore, because ye know not the day nor the hour, He means that all that has been said points to this, namely, that seeing we know not the day of judgment, we should be careful in providing the light of good works.