So that he does not come suddenly and find you asleep.
Sleep here is an image of spiritual indifference. A person may be outwardly religious, yet inwardly asleep, having lost the sense of repentance, the fire of prayer, and the expectation of the Lord’s coming. The coming of Christ will be sudden for those who live in the security of this world and do not wait for Him. This word is a warning given in love. The Lord does not want His servants to be found in shame, but to meet Him prepared, faithfully, and with joy.