"The Messenger of Allah ﷺ 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.'" (Using translation from Tirmidhī 2140)
كَانَ النَّبِيُّ ﷺ يُكْثِرُ أَنْ يَقُولَ يَا مُقَلِّبَ الْقُلُوبِ ثَبِّتْ قَلْبِي عَلَى دِينِكَ قَالَ فَقُلْنَا يَا رَسُولَ اللهِ آمَنَّا بِكَ وَبِمَا جِئْتَ بِهِ فَهَلْ تَخَافُ عَلَيْنَا؟ قَالَ فَقَالَ نَعَمْ إِنَّ الْقُلُوبَ بَيْنَ أُصْبُعَيْنِ مِنْ أَصَابِعِ اللهِ ﷻ يُقَلِّبُهَا