Mark continued with another unique saying of Jesus about being vigilant, a continual theme. Jesus said to all of them (ὃ δὲ ὑμῖν λέγω, πᾶσιν λέγω) just be vigilant, watchful, alert, or awake (γρηγορεῖτε), no sleeping on the job!
This parable ending saying is unique to Matthew. This is the famous remark about the end times. Jesus said that they were to keep awake, to watch and be vigilant all the time (Γρηγορεῖτε οὖν), because they did not know (ὅτι οὐκ οἴδατε) the day (τὴν ἡμέραν) or the hour (τὴν ἡμέραν) when the end would come. This was a simple message to be vigilant all the time because your end or the end of the world could happen at any time.