"And the Eternal, your G‑d, will circumcise your heart." (Deut. 30:6)

It is this which the Rabbis have said, that if someone comes to purify himself, they assist him [from on High]. The verse assures you that you will return to Him with all your heart and He will help you.

This following subject is very apparent from Scripture: Since the time of Creation, man has had the power to do as he pleased, to be righteous or wicked. This grant of free will applies likewise to the entire Torah-period, so that people can gain merit upon choosing the good and punishment for preferring evil. But in the days of the Mashiach, the choice of genuine good will be natural; the heart will not desire the improper and one will have no craving whatsoever for it.

Since the time of Creation, man has had the power to do as he pleased, to be righteous or wicked….

This is the "circumcision" mentioned here, for lust and desire are the "foreskin" of the heart, and circumcision of the heart means that it will not covet or desire evil. Man will return at that time to what he was before the sin of Adam, when by his nature he did what should properly be done, and there were no conflicting desires in his will, as I have explained in [my commentary on] the book of Genesis.

In the days of the Mashiach, there will be no evil desire in man….

Now, it is known that "the imagination of man's heart is evil from his youth" and it is necessary to instruct them, but at that time it will not be necessary to instruct them [to avoid evil] for their evil instinct will then be completely abolished. And so it is declared by Ezekiel, "A new heart I will also give you, and a new spirit will put within you; and I will cause you to walk in My statutes." The new heart alludes to man's nature, and the new spirit to the desire and will.

It is this which our Rabbis have said: And the years draw nigh, when you will say: 'I have no pleasure in them' - these are the days of the Mashiach, as they will offer opportunity neither for merit nor for guilt." For in the days of the Mashiach, there will be no evil desire in man but he will naturally perform the proper deeds, and therefore there will be neither merit nor guilt in them, for merit and guilt are dependent upon desire.

[Adapted from Rabbi Dr. Charles Chavel's annotated translation.]