Parashas Eikev · Passuk 10:12
And now, O Israel, what does the ETERNAL your God demand of you? Only this: to revere the ETERNAL your God, to walk only in divine paths, to love and to serve the ETERNAL your God with all your heart and soul,
Torah Temimah points to Berachos 33b.
TT lemma: כי אם ליראה (unit 2 of 4).
English: R’ Chanina said: Everything is in the hands of Heaven except the fear of Heaven, as it is said, “What does Hashem your God ask of you? Only to fear Hashem.”
Custom (everything in Heaven’s hands except yirat Shamayim)
Yirat Shamayim is the one domain God leaves entirely to human choice; from it the other demands of the verse unfold.