Targum Pseudo-Jonathan on Exodus 15:26 translates the covenant at Marah with a surgeon's precision. The Word of the Lord says: If you will truly hearken to the Word of the Lord your God, and do that which is right before Him, and will listen to His precepts and keep all His statutes, all those evil things that I laid upon the Mizraee I will not lay upon thee: but if thou wilt transgress against the word of the law, upon thee shall they be sent. If thou convert, I will remove them from thee; for I am the Lord thy Healer.
Read it carefully. The Targum preserves the conditionality of the Hebrew, but it sharpens two points.
First: those evil things I laid upon the Mizraee. The plagues are not abstract diseases. They are specific historical punishments, tailored to Egypt. Israel is being told, explicitly, that the same arsenal of plagues that broke Pharaoh is available for use against them if they break covenant. The God who liberates is the same God who judges. You do not get the exodus without the implicit warning.
Second, and this is the Targum's great kindness: if thou convert, I will remove them from thee. The Aramaic tetavun means "you return," the same verb as teshuvah, repentance. The plagues are not permanent fixtures. They are removable by return. The final phrase seals it: for I am the Lord thy Healer. He is not only the one who strikes. He is, by name, the one who heals.
The Maggid catches the medical metaphor. A doctor who only diagnoses is useless. A doctor who only treats is reckless. A healer, in the Targum's sense, is a doctor who sees the illness clearly and also knows the cure. That is how the Holy One describes Himself at Marah.
Takeaway: the plagues that Egypt received and Israel was spared are not trophies. They are instruments, still in the cabinet, kept there by the same Healer who promises to return them if we return from our <a href='/categories/midrash-aggadah.html'>wayward path</a>.