Dua when you visit a sick person

عن عائشة رضي الله عنها أَن النبيَّ صَلّى اللهُ عَلَيْهِ وسَلَّم كَانَ يعُودُ بَعْضَ أَهْلِهِ يَمْسَحُ بيدِهِ اليُمْنى ويقولُ : « اللَّهُمَّ ربَّ النَّاسِ ، أَذْهِب الْبَأسَ ، واشْفِ ، أَنْتَ الشَّافي لا شِفَاءَ إِلاَّ شِفَاؤُكَ ، شِفاءً لا يُغَادِرُ سقَماً » متفقٌ عليه .

Hadhrat Aishah (رضي الله عنها):narrates that When the Prophet (صلى الله عليه وسلم) visited any ailing member of his family, he would touch the sick person with his right hand and would supplicate: "Allahumma Rabban-nasi, adhhibil-ba'sa, washfi, Antash-Shafi, la shifa'a illa shifa'uka, shifaan la yughadiru saqaman [O Allah! the Rubb of mankind! Remove this disease and cure (him or her)! You are the Great Curer. There is no cure but through You, which leaves behind no disease]."
[Al-Bukhari and Muslim].