John Calvin on Leviticus 19:1-2

1. And the Lord spake. This is the object of the exhortation: first, that they should not measure the service of God by their own conceits, but rather by His nature; and secondly, that they should begin by studying “Pour le servir deuement, ils commencent par ce bout, de se purifier de toutes souillures;” in order to serve Him duly, they should begin by purifying themselves from all uncleanness — Fr. to be holy. For nothing is harder than for men to divest themselves of their carnal affections to prepare for imitating God. Besides, they willingly lie slumbering in their own filthiness, and seek to cloak it by the outward appearance of religion. Here, then, they are recalled to the imitation of God, who, in adopting them, desired that they should bear His image, just as good and undegenerate children resemble their father. If any should pretend to equal God, his emulation would be madness; but although the most perfect come very far short even of the angels, yet the weakness of the very humblest does not prevent him from aspiring after the example of God. To this point did all the ceremonies tend, whereby God exercised His ancient people unto holiness, as we shall hereafter see. Although this declaration does not occur once only, yet because it is annexed in other places to special precepts in order to their confirmation, let it suffice at present to apprehend the general doctrine it contains.

Deuteronomy 6

Deuteronomy 6:14, 15

14. Ye shall not go after other gods, of the gods of the people which are round about you;

14. Non ambulabitis post deos alienos e diis populorum qui undique circum vos sunt:

15. (For the Lord thy God is a jealous God among you;) lest the anger of the Lord thy God be kindled against thee, and destroy thee from off the face of the earth.

15. Quoniam Deus zelotes Jehova Deus tuus in medio tui est: ne forte irascatur furor Jehovae Dei tui in to, et disperdat te e superficie terrae.