Theophylact of Ohrid — as excerpted in the Catena Aurea on Mark 13:32-37

“See again that He has not said, I know not when the time will be, but, Ye know not. For the reason why He concealed it was that it was better for us; for if, now that we know not the end, we are careless, what should we do if we knew it? We should keep on our wickednesses even unto the end. Let us therefore attend to His words; for the end comes at even, when a man dies in old age; at midnight, when he dies in the midst of his youth; and at cockcrow, when our reason is perfect within us; for when a child begins to live according to his reason, then the cock cries loud within him, rousing him from the sleep of sense; but the age of childhood is the morning. Now all these ages must look out for the end; for even a child must be watched, lest he die unbaptized.”