Rashi on Exodus 15:26/רש"י על שמות ט״ו:כ״ו

1אם שמע תשמע IF THOU WILL DILIGENTLY HEARKEN — this implies acceptance — that they should take upon themselves the duty of performing God’s commands.

2תעשה AND IF THOU WILT DO — this implies the performance of the commands.

3והאזנת means THOU WILT INCLINE THE EAR to be punctilious in the practice of the details.

4כל חקיו ALL HIS STATUTES — Matters which are only the decrees of the King (decrees of God imposed by Him, as King, upon us, His subjects) and which appear to have no reason, and at which the evil inclination cavils saying, “What sense is there in prohibiting these? Why should they be prohibited?” — For instance: the prohibition of wearing a mixture of wool and linen, and of eating swine’s flesh, and the law regarding the red heifer, and similar matters (cf. Yoma 67b).

5לא אשים עליך I WILL NOT PLACE ON THEE — and if I do place them on thee because thou refusest to hearken to My voice, it will be as though they had not been placed on thee, for if thou repentest of thy disobedience I will remove them immediately, כי אני ה׳ רפאך BECAUSE I AM THE LORD THAT HEALETH THEE. This is its Midrashic explanation (Mekhilta). But according to its literal sense the meaning is: For I am the Lord who healeth thee and teacheth thee the Law and Commandments in order that thou mayst be saved from them (these diseases) — like a physician who says to a man: Do not eat this thing lest it will bring you into danger from this disease. So, too, it states, (Proverbs 3:8) “It (obedience to God) will be wholesome to thy body” (implying that disease will not fall upon thee) (Mekhilta).