Mt 4:10, Lc 4:8 and Dt 6:13, 10:20 : from where did Jesus take this “only” in “him only shalt thou serve”?

I searched in the LXX, OT massoretic text but I didn’t find one place where we have a such "only" equivalent in scripture, yet J.C seems to cite it as a scripture ! If you have any answer on that ! (I wonder what the targumim say…