Du'a when visiting the sick
اللَّهُمَّ رَبَّ النَّاسِ، أَذْهِبِ الْبَأْسَ، اشْفِهِ وَأَنْتَ الشَّافِي، لَا شِفَاءَ إِلَّا شِفَاؤُكَ
Allaahumma rabban-naas, adh-hibil-ba's, ishfihi wa antash-shaafee, laa shifaa'a illaa shifaa'uk.
O Allah, Lord of mankind, remove the harm. Cure him, for You are the Healer. There is no cure except Your cure.
Source: Sahih al-Bukhari 5743