"The Messenger of Allah (saas) often used to say: 'Allahumma thabbit qalbi 'ala dinika [O Allah, make my heart steadfast in (adhering to) Your religion].' A man said: 'O Messenger of Allah! Do you fear for us when we have believed in you and in (the Message) that you have brought?' He said: 'Hearts are between two of the fingers of the Most Merciful, and He controls them.'" (Hasan)Al-A'mash (one of the narrators) indicated with his fingers.
كَانَ رَسُولُ اللَّهِ ﷺ يُكْثِرُ أَنْ يَقُولَ اللَّهُمَّ ثَبِّتْ قَلْبِي عَلَى دِينِكَ فَقَالَ رَجُلٌ يَا رَسُولَ اللَّهِ تَخَافُ عَلَيْنَا وَقَدْ آمَنَّا بِكَ وَصَدَّقْنَاكَ بِمَا جِئْتَ بِهِ فَقَالَ إِنَّ الْقُلُوبَ بَيْنَ إِصْبَعَيْنِ مِنْ أَصَابِعِ الرَّحْمَنِ ﷻ يُقَلِّبُهَا وَأَشَارَ الأَعْمَشُ بِإِصْبَعَيْهِ