"There is no Muslim worshiper who visits one who is ill - other than at the time of death - and he says seven times: As'alullah Al-'Azeem Rabbal 'Arshil 'Azeem an yashfik ('I ask Allah the Magnificent, Lord of the Magnificent Throne to cure you') except when he will be cured." (Using translation from Tirmidhī 2083)  

عَنِ النَّبِيِّ ﷺ قَالَ «مَا مِنْ عَبْدٍ مُسْلِمٍ يَعُودُ مَرِيضًا لَمْ يَحْضُرْ أَجَلُهُ فَيَقُولُ سَبْعَ مَرَّاتٍ أَسْأَلُ اللَّهَ الْعَظِيمَ رَبَّ الْعَرْشِ الْعَظِيمِ أَنْ يَشْفِيَكَ إِلَّا عُوفِيَ»