Anas bin Malik reported,
The Prophet ﷺ used to say often, "Turner of hearts, keep my heart firm upon Your religion."We said, "Messenger of Allah, we believe in you and in what you have brought. Do you still fear for us?"He replied, "Yes. Hearts are between two of the fingers of Allah 
, and He turns them as He wills."
Ahmad 12107
Sahihحدثنا أبو معاوية عن الأعمش عن أبي سفيان
عن أنس قال
كان النبي ﷺ يكثر أن يقول يا مقلب القلوب ثبت قلبي على دينك قال فقلنا يا رسول الله آمنا بك وبما جئت به فهل تخاف علينا قال فقال نعم إن القلوب بين أصبعين من أصابع الله عز وجل يقلبها
Its isnad is sahih. Abu Sufyan is Talha bin Nafi. The hadith was narrated by Muslim 4/2045, no. 2654, in the chapter on divine decree, on Allah's turning of the hearts as He wills, by Tirmidhi 4/448, no. 2140, who graded it sahih, and by Ibn Majah 2/1260, no. 2140, in the chapter on supplication, on the supplication of the Messenger of Allah ﷺ.