In the Torah, God says:
קְדֹשִׁ֣ים תִּהְי֑וּ כִּ֣י קָד֔וֹשׁ אֲנִ֖י יְהֹוָ֥ה אֱלֹהֵיכֶֽם׃ -- You shall be holy, because I, your God יהוה, am holy. [Lev. 19:2]
The Ramban famously explained that this means we should restrain ourselves even with what is permitted:
The meaning of "You shall be holy" is as follows: The Torah has admonished us against immorality and forbidden foods, but permitted sexual intercourse between man and his wife, and the eating of [certain] meat and wine. If so, a man of desire could consider this to be a permission to be passionately addicted to sexual intercourse with his wife or many wives [even in public], and be among winebibbers, among gluttonous eaters of flesh, and speak freely all profanities, since this prohibition has not been [expressly] mentioned in the Torah, and thus he will become a vile, disgusting person with the permission of the Torah!
If so, I don't understand the addition "because I, the Lord your God, am holy." Does God "restrain" Himself with what is "permitted" to Him? What do the words even mean in this context?