“You shall not rove after your heart” – the heart and the eyes are the mediators of the body, as they cause the body to stray. “So that you will remember, and perform all My commandments” – this is analogous to one cast into the water. The captain extended the rope and said to him: ‘Grasp this rope in your hand and do not let it go, as if you let it go, you will have no life.’ This, too, is what the Holy One blessed be He said to Israel: ‘As long as you cleave to the mitzvot – “but you, who cleave to the Lord your God, all of you live today”’ (Deuteronomy 4:4).
Likewise it says: “Hold fast to admonition, do not let go; safeguard it, as it is your life” (Proverbs 4:13). “And be holy” – when you perform the mitzvot, you are sanctified, and dread of you will be cast over the idolaters. If you forsake the mitzvot, you become profaned. The Holy One blessed be He said to Israel: ‘In this world, by means of the evil inclination you forsake the mitzvot, but in the future, I will uproot it from you,’ as it is stated: “And I will place My spirit within you, [and I will act so that you will follow My statutes, and My ordinances you will observe and perform]” (Ezekiel 36:27).