TT #113 · Parashas Shoftim · Second Aliyah · Passuk 17:19
And it shall be with him, and he shall read in it all the days of his life, so that he may learn to fear the Eternal his God, to keep all the words of this Torah and these statutes, to do them.
Torah Temimah points to Sifrei Devarim 161.
TT lemma: וְאֶת הַחֻקִּים הָאֵלֶּה לַעֲשׂוֹתָם.
English: ‘And these statutes, to do them’ – for the doing is the main thing.
Derash emphasizing practice (Sifrei) — the ultimate purpose of the king’s reading is practical fulfillment of the mitzvos.
The king’s Torah study must lead to action. Knowledge without observance is incomplete.