And this is love - That is, our love is shown and proved by our walking according to the commandments of God; for love is the principle of obedience.
And this is love, that we walk after his commandments - This is the proper expression or evidence of love to God. See the notes at John 14:15, John 14:21.
This is the commandment - That is, this is his great and special commandment; the one by which his disciples are to be especially characterized, and by which they are to be distinguished in the world. See the notes at John 13:34.