Jami` at-Tirmidhi Book 48, Hadith 218
“I entered upon the Prophet (ﷺ) while he was praying and he had placed his left hand on his left thigh, and he had placed his right hand on his right thigh, and clasped his fingers, and extended his index finger, and he was saying: ‘O changer of the hearts, make my heart firm upon Your religion (Yā muqallibal-qulūbi thabbit qalbī `alā dīnik).’”
“The Messenger of Allah (ﷺ) taught me, saying: ‘Say: “O Allah, make my secret better than my apparent condition, and make my apparent condition righteous. O Allah, I ask You for the righteous of what you give to the people, of wealth, wives, and children, not (to be) misguided, nor misguiding. (Allāhummaj`al sarīratī khairan min `alāniyatī waj`al `alāniyatī ṣāliha. Allāhumma innī as’aluka min ṣālihi mā tu’tin-nāsa minal-māli wal-ahli wal waladi, ghairaḍ-ḍāli wa lal-muḍil).”
“Thabit Al-Bunani narrated to me, he said to me: ‘O Muhammad, when you suffer from some ailment, then place your hand at the place of the ailment, then say: “In the Name of Allah, I seek refuge in Allah’s might and power from the evil of this pain I feel (Bismillāh, a`ūdhu bi-`izzatillāhi wa qudratihī min sharri mā ajidu min waja`ī hādhā).” Then lift your hand and repeat that an odd number of times. For indeed, Anas bin Malik narrated to me, that the Messenger of Allah (ﷺ) narrated that to him.’”