2 By this we know that we love the children of God, whenever we love God and keep His commandments.
1 John 5:2 Cross References - CAB
John 13:34-35
John 15:17
17 These things I command you, that you may love one another.
1 John 2:5
5 But whoever keeps His word, truly the love of God is perfected in him. By this we know that we are in Him.
1 John 3:22-24
22 And whatever we should ask we receive from Him, because we keep His commandments and we do the things pleasing before Him.
23 And this is His commandment: that we should believe in the name of His Son Jesus Christ and should love one another, just as He gave commandment.
24 And the one who keeps His commandments abides in Him, and He in him. And by this we know that He abides in us, from the Spirit whom He gave us.
1 John 4:21
21 And this commandment we have from Him: that he who loves God should love his brother also.