Jerome,
Letters 13.1 (
Corpus Scriptorum Ecclesiasticorum Latinorum, vol. 54, pp. 42-43; tr. Charles Christopher Mierow):
John the apostle and evangelist says in his Epistle [1 John 3.15]: Whosoever hateth his brother is a murderer. And he is right.
Since murder has its origin in hatred, whosoever hates, even
though he has not yet struck a blow with the sword, is nevertheless a murderer at heart.
Ioannes idem apostolus et evangelista in epistula sua ait: quicumque odit fratrem suum, homicida, et recte. cum enim homicidium ex odio saepe nascatur, quicumque odit, etiam si necdum gladio percusserit, animo tamen homicida est.
1 John 3.15:
πᾶς ὁ μισῶν τὸν ἀδελφὸν αὐτοῦ ἀνθρωποκτόνος ἐστίν, καὶ οἴδατε ὅτι πᾶς ἀνθρωποκτόνος οὐκ ἔχει ζωὴν αἰώνιον ἐν αὐτῷ μένουσαν.