1 John 4:20

If any one say, I love God, and hate 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 does not keep his commandments, is a liar, and the truth is not in him;

1 John 2:9

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

1 John 3:17

But whoso may have the world's substance, and see his brother having need, and shut up his bowels from him, how abides the love of God in him?

1 John 4:12

No one has seen God at any time: if we love one another, God abides in us, and his love is perfected in us.

1 John 2:11

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

1 Peter 1:8

whom, having not seen, ye love; on whom though not now looking, but believing, ye exult with joy unspeakable and filled with the glory,

1 John 1:6

If we say that we have fellowship with him, and walk in darkness, we lie, and do not practise 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 does not keep his commandments, is a liar, and the truth is not in him;
1 John 3:17
But whoso may have the world's substance, and see his brother having need, and shut up his bowels from him, how abides the love of God in him?

Not

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

General references

Matthew 22:40
On these two commandments the whole law and the prophets hang.
Matthew 25:42
for I hungered, and ye gave me not to eat; I thirsted, and ye gave me not to drink;
John 13:35
By this shall all know that ye are disciples of mine, if ye have love amongst yourselves.
John 14:15
If ye love me, keep my commandments.
Hebrews 13:1
Let brotherly love abide.