Mark 13:37

And what I say unto you I say unto all, Watch.

With so much information given them, the disciples might have thought that they ought to know the exact date of Christ's second advent, for that would greatly simplify matters. But Christ rejects the idea before it has been voiced. Of the day when the final judgment will burst upon the world and of the hour of the day when its first indications will come to pass, no person knows; even the angels are ignorant, though they know many of the secrets and mysteries of God. A what is more, the day is not known to Jesus in His state of humiliation. The Son of God, in His capacity as Savior of men and specifically according to His human nature, has renounced His right to this knowledge, chiefly for the sake of men, lest they be tempted to make inquiries and bother Him with importunate pleadings concerning the day and the hour. Here is a secret which is hidden in the omniscience of the Father. But that fact brings out Christ's admonition all the more strongly: Be on the lookout, be vigilant, for the exact time is not known upon earth. All the calculations of the various sects as to the exact date of Christ's coming are utterly unreliable vagaries, and those that follow them are just as foolish. This is brought out in another parable. When the master of a household who has business in a distant part of the country or in a far country is called away he will leave his house in charge of his servants, distributing the work according to the ability of each and giving to everyone some authority and responsibility, each one thus being put on his honor. The porter will be singled out for a special warning, lest he be asleep at his post. Thus Jesus, the Lord of His Church, has given to each one of His believers, His servants, some work to do, some ability, some gifts, with which the individual Christian is to serve Him in His kingdom. The Lord will return some time, soon, almost any minute, and therefore it is necessary for every one of the servants to be about his business with careful vigilance. The Master may come in any of the four watches of the night, and His coming must find no one sleeping in security. The picture reminds us of the custom of watching in the Temple. This was in the hands of a certain number of priests and Levites, whose business was a sleepless vigilance. At any time during the night, no one knew in which watch, the chief of the Temple-service might make his rounds. And woe to him that was caught asleep at that time! Much more important, however, is the necessity which is laid upon all the disciples of Christ not to become drowsy, listless, and negligent in the Master's work or in constant watching for His coming. Let every Christian write upon the portals of his heart that one word: Watch! It is very true, indeed, that the unbelievers think it a huge joke to ridicule the belief of the Christians about the coming of Judgment Day: Where is the promise of His coming? for since the fathers fell asleep, all things continue as they were from the beginning of creation, 2 Peter 3:3. At the same time, however, those very scoffers are the first ones, during a storm or at the time of an earthquake, or in the presence of some other extraordinary manifestation of God in nature, to fall upon their knees and implore God's mercy. It is absolutely safe to stand on God's word and to heed His warning at all times: Watch!

Summary. Answering several questions of His disciples, Jesus foretells the destruction of Jerusalem and the Temple, predicts the devastation of the Jewish country, mentioning a number of signs that would precede such judgment of God, also prophesies of the end of the world and tells several short parables to impress upon every one the necessity to watch.