أَسْـأَلُ اللهَ العَـظيـم، رَبَّ العَـرْشِ العَـظيـم أَنْ يَشْفـيك . (سبع مرات
As'alullāha ‘l-`Aẓīma Rabba ‘l-`Arshil-`Aẓīmi an yashfiyak.
I ask Almighty Allah, Lord of the Magnificent Throne, to make you well. (Recite seven times in Arabic .)
At-Tirmidhi, Abu Dawud. See also Al-Albani, Sahih At-Tirmidhi 2/210 and Sahihul-Jami' As-Saghir 5/180.