פירוש על מכות 46:9

So that they can receive reward by virtue of holding themselves back from transgressions. Therefore, [God] increased [the number of commandments] for them. [God] did not need to command them so many commandments regarding vermin and carcasses which people naturally can't stand, but did so in order to give people reward for avoiding them.

248 positive commandments - For each and every limb says to him, "do a mitzvah."

365 negative commandments - For every day, they warn him to not transgress.