1 John 4:21

And this commandment have we from him
Either "from God", as the Alexandrian copy and the Vulgate Latin version read; and that to love the brethren is a commandment of God, is clear from ( 1 John 3:23 ) ; or from Christ, for it is also a command of his, even his new commandment, which he has given, and his people have received from him:

that he who loveth God, love his brother also;
see ( John 13:34 ) ( John 15:12 John 15:17 ) ; which is an argument persuading to attend to the one as well as to the other; for the same command that requires the one, requires the other: and he that transgresses it in one case, is a transgressor of it, as well as in the other.