Halakhah for Menachot 86:12

From the roots of the commandment is to remember the miracles of Egypt, as we have written in the other [related commandments]. And this is also a trunk from the root mentioned: For it is not honorable for the sons of kings and the advisers of the land to drag the bones and break them like dogs. Except for the impoverished among the people and the starving, it is not a proper thing to do this. And therefore, as we began to become the chosen of all nations, 'a kingdom of priests and a holy nation' - and in each and every year at that time - it is fitting for us to do acts that show the great stature which we achieved at that hour, about us. And in the act and reenactment that we do, this thing is placed in our souls for eternity. My son, do not think to pounce upon my words and say, "Why would God, may He be blessed, command us to do all of these commandments to commemorate that miracle; would we not remember it with one commemoration, [such that] it not be forgotten from the mouth of our offspring?" You must know that it is not from wisdom that you would [question] me about this, and it is your youthful thoughts that lead you to this. And now, my son, 'If you have understanding,' 'incline your ear and hear,' and I will teach you to benefit from Torah and the commandments: You must know, that a man is acted upon according to his actions; and his heart and all his thoughts always follow after the actions that he does - whether good or bad. And even he who in his heart is a complete sinner and all the desires of his heart are only for evil; if his spirit shall be enlightened and he will put his efforts and actions to persist in Torah and commandments - even if not for the sake of Heaven - he shall immediately incline towards the good. And from that which is not for its own sake comes that which is for its own sake [as opposed to being for personal gain]; for the hearts are drawn after the actions. And even if a man is perfectly righteous and his heart is straight and innocent, desiring of Torah and the commandments; if he shall constantly deal with improper things, you could compare it to someone who was forced by the king to work a wicked craft - if he constantly works in that wicked craft - eventually, from his righteousness, he shall have become completely evil. For it is known and true that every man is acted upon according to his actions, as we have said. And the Sages, may their memory be blessed, said about this (Makkot 23b), "God wanted to grant merits to Israel, therefore he gave them many laws and commandments," to occupy all of our thoughts and all our deeds, to benefit us at our end [i.e. in the world to come]. Because from the good actions we are acted upon to be good and merit eternal life. And the Sages hinted at this (Menachot 43b) with their statement that anyone who has a mezuzah on his door, tsitsit on his garment and tefillin on his head is promised that he shall not sin - for these are constant commandments, and [so] he is constantly acted upon by them.