Musar su Levitico 21:3

There are many different ways the 248 positive and 365 negative commandments have been counted. The earliest compiler and the most authoritative one has been the author of הלכות גדולות, followed by the great scholar Shlomo Gabirol and subsequently the great master Maimonides. There followed Rabbi Moshe from Kotzi known as the סמ"ג or ספר מצות גדולות. The fact that we find far earlier attempts to determine how certain laws are derived from the written Torah, such as during the time of Rabbi Akiva and later Talmudic scholars, does not make those scholars we just mentioned arbiters as to who among the earlier scholars is correct. To mention just one example of different views, take the law of the סוטה, Numbers 5,14. It is debated whether the Torah when discussing the husbands's jealousy of his wife (and all the procedures prescribed when there is insufficient prima facie evidence of marital infidelity on her part) is something that is merely his right, or whether it is his duty. Whereas Rabbi Yishmael considers this merely a husband's privilege, Rabbi Akiva considers it the husband's duty. There are numerous disagreements between these two scholars concerning whether certain statements in the written Torah are merely indications of a permissible course of action or whether they make it mandatory.