Muhammad bin 'Amr bin 'Alqama محمد بن عمرو بن علقمة · Chapters On Al-Qadar

"The Messenger of Allah (s.a.w) would often say: Ya Muqallibal-qulub, thabbit qalbi 'ala dinik('O Changer of the Hearts! Strengthen my heart upon Your Religion.)' So I said: 'O Prophet of Allah! We believe in you and what you have come with, but do you fear for us?' He said: 'Yes. Indeed the hearts are between two Fingers of Allah's Fingers, He changes them as He wills.'"