“But know this, that if the goodman of the house had known in what watch the thief would come, he would have watched, and would not have suffered his house to be broken up.”
Matthew 24:43 — Greek Interlinear
Church Fathers on Matthew 24:43
Having declared that 'of that hour knoweth no man, but the Father only,' He shews that it was not expedient for the Apostles to know, that being ignorant they might live in perpetual expectation of His coming, and thus concluding the whole, He says, 'Watch therefore, &c.' And He does not say, 'Because we know not,' but 'Because ye know not,' shewing that He Himself is not ignorant of the day of judgment.
He would have them ever ready, and therefore He says, 'Watch.'
To watch is to keep the eyes open, and looking out for the true light, to do and to observe that which one believes, to cast away the darkness of sloth and negligence.