Pensée juive sur Rois 2 2:19

וַיֹּ֨אמְר֜וּ אַנְשֵׁ֤י הָעִיר֙ אֶל־אֱלִישָׁ֔ע הִנֵּה־נָ֞א מוֹשַׁ֤ב הָעִיר֙ ט֔וֹב כַּאֲשֶׁ֥ר אֲדֹנִ֖י רֹאֶ֑ה וְהַמַּ֥יִם רָעִ֖ים וְהָאָ֥רֶץ מְשַׁכָּֽלֶת׃

Or, les habitants de Jéricho dirent à Élisée: "Le séjour de cette ville est agréable, comme mon seigneur le voit; mais l’eau y est malsaine et le sol meurtrier."

Duties of the Heart

It is even possible that He will heal him through something that is normally very harmful, as you know from the story of Elisha and the bad water, that he healed their damaging properties with salt (Melachim II 2:19), and similarly "And G-d showed him a tree and he tossed it into the waters [and the waters became sweet]" (Shmos 15:25), And the midrash tanchuma there explains that this was a bitter, oleander tree. Another example, "let him smear crushed figs on the boils, and he will heal" (Yeshaya 38:21) (and figs normally damage even healthy flesh - PL). And you already know of what happened to the pious king Asa when he trusted in the doctors, and removed his trust in G-d regarding his illness, the sharp rebuke he received for this (i.e. because he did not pray to be healed). And the verse says: "For He brings pain and binds it; He wounds, and His hands heal." (Iyov 5:18).