“What we have proved concerning the love of God, the summary of the first table of the law; namely, that it is good in nature; might be also proved from the summary of the second table, the love of our neighbour.
For he who loves God cannot but love His image too, in which he clearly views express characters of the Deity, and not a small degree of the brightness of His glory.
Again, whoever loves God will, by virtue of that love, seriously wish, desire, study, and as much as in him lies be careful, that his neighbour, as well as himself, be under God, in God, and for God, and all he has be for His glory.
Again, whoever loves God will make it his business that God may appear every way admirable and glorious; and as He appears such most eminently in the sanctification and happiness of men, (2 Thess. 1:10), he will exert himself to the utmost that his neighbour make advances to holiness and happiness.
Finally, whoever sincerely loves God will never think he loves and glorifies Him enough; such excellencies he discovers in Him, sees His name so illustrious, and so exalted above all praise, as to long that all mankind, nay all creatures, should join him in loving and celebrating the infinite perfections of God.
But this is the most faithful and pure love of our neighbour, to seek that God may be glorified in him, and he himself be for the glory of God.
Hence it appears, that the love of our neighbour is inseparably connected with the love of God.
If, therefore, it flows from the nature of God, to enjoin us the love of Himself, as was just proved; it must likewise flow from the nature of God, to enjoin us the love of our neighbour.”
–Herman Witsius, The Economy of the Covenants Between God and Man, Volume 1 (Grand Rapids, MI: Reformation Heritage, 1681/2021), 1: 43–44.