“watch yourselves.” This could be “watch your souls,” or even guard your souls, where “your soul” means yourself. The text is telling us that it takes a certain amount of diligence to love Yahweh. There are many forces against it: our own sin nature and the pull of the ungodly society around us.

[For more on the biblical use of “soul” see Appendix 7, “Usages of ‘soul.’”]