Yaela
You are doing an admirable thing by covering at least to some extent while trying to make sense of what you are doing.
You write that “It’s taken from Parshat Sotah and inferred from that. It’s not stated outright.”
Consider for a moment: You wouldn’t consider keeping kosher any differently, yet the only thing written in the chumash (actually, several times) is ?? ??????? ??? ???? ???. That’s it.
So it is quite clear that we can’t just go by ???? ?????, but we need ???? ???? ?? also.
I had a wise teacher in yeshiva who would say, “Ask away all your questions, but do what needs to be done in the meantime. And even if you don’t get your answers, do it anyway!”