Reference for Berakhot 119:29
אמר אביי לא לימא אינש הכי דתני דבי רבי ישמעאל (שמות כא, יט) ורפא ירפא מכאן שניתנה רשות לרופא לרפאות
Abbai declared : Let not a man speak thus ; for there is a teaching of the school of R. Ishmael : [It is written,] "Only he shall pay for the loss of his time, and shall cause him to be thoroughly healed" (Exod. xxi. 19) ; from this [it follows] that a physician is given permission [by God] to cure.
Jastrow
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Shulchan Arukh, Orach Chayim
One who goes to let blood should say: May it be Your will, my God, that this be an action of healing, for You heal freely. After the bloodletting, say: Blessed... is the healer of the sick.
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