Maghen Abraham - Thoughts From Mayer Sasson

War against whom?

Rashi explained the verse "When you go out to war...." as follows: "This refers to an optional war"- and it is well known how the rabbis in the holy books explained that this alludes to the war against one's Evil Inclination.

We learn from Rashi that a Jew's main war against his Evil Inclination must be not only pertaining to the 248 positive commandments and the 365 negative commandments – rather it is also on optional maters, that one should sanctify himself in permissible matters (i.e. even in matters permissible in the Torah one should sanctify himself and not exaggerate, such as sleeping, eating, etc.) for it is only thereby that he will be able to guard himself not to transgress a mitzvah in the Torah.

However, if one does not sanctify himself in permissible matters and pursues worldly pleasures that are permissible, he will thereby bring his Evil Inclination over him and it will be able to induce him, G-d forbid, to transgress over mitzvahs as well – as the Ramban explains on the verse in Parshat Kedoshim "Be holy because I am holy...." - A person should sanctify himself in permissible matters as well.

SHABBAT SHALOM!!