“If you will heed the LORD your God diligently, doing what is upright in His sight, giving ear to His commandments and keeping all His laws, then I will not bring upon you any of the diseases that I brought upon the Egyptians, for I the LORD am your healer.”
דְּאָמַר רַב אַחָא: הַנִּכְנָס לְהַקִּיז דָּם, אוֹמֵר: ״יְהִי רָצוֹן מִלְּפָנֶיךָ ה׳ אֱלֹקַי שֶׁיְּהֵא עֵסֶק זֶה לִי לִרְפוּאָה, וּתְרַפְּאֵנִי. כִּי אֵל רוֹפֵא נֶאֱמָן אָתָּה וּרְפוּאָתְךָ אֱמֶת, לְפִי שֶׁאֵין דַּרְכָּן שֶׁל בְּנֵי אָדָם לְרַפּאוֹת אֶלָּא שֶׁנָּהֲגוּ״. אָמַר אַבָּיֵי: לָא לֵימָא אִינָשׁ הָכִי, דְּתָנֵי דְּבֵי רַבִּי יִשְׁמָעֵאל: ״וְרַפֹּא יְרַפֵּא״ — מִכָּאן שֶׁנִּיתְּנָה רְשׁוּת לָרוֹפֵא לְרַפּאוֹת. כִּי קָאֵי מַאי אוֹמֵר? — אָמַר רַב אַחָא: ״בָּרוּךְ … רוֹפֵא חִנָּם״.
Oxford 366:
ברוך רופא חיים
Paris 671:
רופא (חולים) חיים
As Rav Aḥa said: One who enters to let blood says:
May it be Your will, O Lord my God, that this enterprise be for healing and that You should heal me. As You are a faithful God of healing and Your healing is truth. Because it is not the way of people to heal, but they have become accustomed.
Abaye responded and said: One should not say this, as it was taught in the school of Rabbi Yishmael that from the verse, “And shall cause him to be thoroughly healed” (Exodus 21:19), from here we derive that permission is granted to a doctor to heal.
When one stands after having let blood, what does he say? Rav Aḥa said: Blessed…Who heals without payment.
It's not the way of people - they shouldn't really be dealing with healing, but praying for mercy.
הנכנס להקיז דם אומר יהר"מ יי אלקי שיהיה עסק זה לי לרפואה. כי רופא חנם אתה וכן קודם שיאכל או ישתה איזה דבר לרפוא' יתפלל תפלה זו ולא יחשוב שתהיה איזה דבר לו לרפואה אלא ע"י הבורא ית"ש ולכן על ידי תפלה זו ישים בטחונו בו ויבקש ממנו שתהא לו לרפוא' ולאחר שהקיז דם אומר בא"י אמ"ה רופא חולים (ט"ז ובה"ג):
One who goes in to let blood should say: May it be Your will, my God, that this matter be for healing. For You heal freely. This applies also before eating or drinking anything to do with healing, this prayer should be said. One should not think that healing comes from anyone but the Blessed Creator, and in saying this prayer, one puts trust in God and asks for healing. After letting blood, one should say: Blessed are You, Ruler of the Universe, who heals the sick.
Not only bloodletting, but anything to do with healing is a cause for this blessing. And one who sneezes, and his friend says "Assuta!" (healing!), s/he should respond 'Blessed be you', and then say 'I hope for Your salvation, God' . For one who prays for another is answered first.
המופת הרביעי, מיום שנברא העולם לא היה אדם חולה, אלא בכל מקום שהיה אדם אם בדרך אם בשוק ועטש היתה נפשו יוצאה מנחיריו ומת, עד שבא יעקב אבינו ובקש רחמים על זאת ואמר לפני הב"ה, רבונו של עולם אל תקח את נפשי ממני עד אשר אני מצוה את בני ובני ביתי. ונעתר לו, שנ' ויהי אחרי הדברים האלה ויאמר ליוסף הנה אביך חולה. ושמעו כל מלכי הארץ ותמהו שלא היה כמהו מיום שנבראו שמים וארץ, לפיכך חייב אדם לומר לחבירו בשעת עטישותיו חיים שנהפך מות העולם לאור, שנ' (איוב מא, י) עטישותיו תהל אור.
From the day when the heavens and the earth were created no man was ill, (who) sneezed and lived, but in every place where he happened to be, whether on the way or in the market, and (when he) sneezed, his soul went out through his nostrils; until our father Jacob came and prayed for mercy concerning this, and he said before the Holy One, blessed be He: Sovereign of all the worlds! Do not take my soul from me until I have charged my sons and my household; and He was entreated of him, as it is said, "And it came to pass after these things, that one said to Joseph, Behold, thy father is sick" (Gen. 48:1). All the kings of the earth heard (thereof), and they wondered because there had been no one like him from the days when the heavens and earth had been created. Therefore a man is in duty bound to say to his fellow: Life! when the latter sneezes, for the death of the world was changed into light, as it is said, "His sneezings flash forth light" (Job 41:18).