1 John 4:20

If a man says, I love God, and hates his brother, he is a liar: for he that loves not his brother whom he has seen, how can he love God whom he has not seen?

1 John 2:4

He that says, I know him, and keeps not his commandments, is a liar, and the truth is not in him.

1 John 2:9

He that says he is in the light, and hates his brother, is in darkness even until now.

1 John 3:17

But whoever has this world's goods, and sees his brother have need, and shuts up his heart of compassion from him, how dwells the love of God in him?

1 John 4:12

No man has seen God at any time. If we love one another, God dwells in us, and his love is perfected in us.

1 John 2:11

But he that hates his brother is in darkness, and walks in darkness, and knows not where he goes, because that darkness has blinded his eyes.

1 Peter 1:8

Whom having not seen, you love; in whom, though now you see him not, yet believing, you rejoice with joy unspeakable and full of glory:

1 John 1:6

If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:

Treasury of Scripture Knowledge

Summary

If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen?

Bible References

A man

1 John 2:4
He that says, I know him, and keeps not his commandments, is a liar, and the truth is not in him.
1 John 3:17
But whoever has this world's goods, and sees his brother have need, and shuts up his heart of compassion from him, how dwells the love of God in him?

Not

1 John 4:12
No man has seen God at any time. If we love one another, God dwells in us, and his love is perfected in us.

General references

Matthew 22:40
On these two commandments hang all the law and the prophets.
Matthew 25:42
For I was hungry, and you gave me no food: I was thirsty, and you gave me no drink:
John 13:35
By this shall all men know that you are my disciples, if you have love one to another.
John 14:15
If you love me, keep my commandments.
Hebrews 13:1
Let brotherly love continue.