أَذْهِبِ الْبَأْسَ رَبَّ النَّاسِ، وَاشْفِ أَنْتَ الشَّافِي، لَا شِفَاءَ إِلَّا شِفَاؤُكَ، شِفَاءً لَا يُغَادِرُ سَقَمًا

Adhhibil-ba’s Rabban-naas, washfi Antash-Shaafi, laa shifaa’a illaa shifaa’uka, shifaa’an laa yughadiru saqama

Take away the disease, O the Lord of the people! Cure him as You are the One Who cures. There is no cure but Yours, a cure that leaves no disease. Whenever Allah's Messenger (ﷺ) paid a visit to a patient, or a patient was brought to him, he used to invoke Allah, saying (The dua is mentioned above)

Reference: Bukhari: 5675