John the Apostle
1 John 2:11BSB·traditional attribution

But whoever hates his brother is in the darkness and walks in the darkness. He does not know where he is going, because the darkness has blinded his eyes.

John Calvin Reformed @genevareformer

11. But he that hateth his brother. He again reminds us, that whatever specious appearance of excellency thou shewest, there is yet nothing but what is sinful if love be absent. This passage may be compared with the thirteenth chapter of the First Epistle to the Corinthians, and no long explanation is needed.

Matthew Henry Presbyterian @wholebiblehenry

The seventh verse may be supposed either to look backward to what immediately preceded (and then it is walking as Christ walked that is here represented as no new, but an old commandment; it is that which the apostles would certainly inculcate wherever they brought Christ's gospel), or to look forward to what the apostle is now going to recommend, and that is the law...

Commenting on 1 John 2:7-11

John Gill Reformed Baptist @doctorgill

But he that hateth his brother is in darkness,.... As is before expressed in Jo1 2:9, to which is added, and walketh in darkness; he goes on in it, and takes delight in it, as dangerous and uncomfortable as it is: and knoweth not whither he goeth; he cannot discern between good and evil; he puts darkness for light, and light for darkness; he sees...