'Command of the Lord' in the Bible

Now concerning the virgins [of marriageable age] I have no command of the Lord, but I give my opinion as one who by the Lord’s mercy is trustworthy.

If anyone thinks and claims that he is a prophet [a true spokesman for God] or spiritually astute [filled with and energized by the Holy Spirit], let him recognize that the things which I write to you are the Lord’s commandment.

If anyone does not recognize this [that it is a command of the Lord], he is not recognized [by God].