When a person is suffering from a serious illness, he should keep asking for this prayer frequently. Allah Almighty healed Hazrat Ayub (as) with the blessing of this prayer. The supplication for healing from illness is given below:
اَنِّىْ مَسَّنِيَ الضُّرُّ وَاَنْتَ اَرْحَمُ الرّٰحِمِيْنَ (۲۱:۸۳)
(O Allah!) Trouble has befallen me and You are the Most Merciful.