'Commandment' in the Bible

Beloved, I write no new commandment to you, but an old commandment, which ye have had from the beginning. The old commandment is the word which ye heard.

Again, I write a new commandment to you, which thing is true in him and in you, because the darkness is passing and the true light already shines.

And this is his commandment, that we believe on the name of his Son Jesus Christ, and that we love one another, even as he has given us commandment.

And this commandment have we from him, That he that loves God love also his brother.