supplications for the heart or qalb ..

 

The full supplication is:

اللَّهُمَّ مُصَرِّفَ الْقُلُوبِ صَرِّفْ قُلُوبَنَا عَلَى طَاعَتِكَ
(Allahumma musarrifal-qulubi, sarrif qulubana 'ala ta'atika) 

Meaning
Translation:

 "O Allah, Controller of hearts, direct our hearts to Your obedience".

Context: 

This prayer emphasizes that human hearts are under Allah's control and asks for divine guidance to keep our intentions and actions aligned with what pleases Him. 

Significance

Source: This dua is recorded in Sahih Muslim.
Similar Supplication:

 It is often mentioned alongside another famous dua:

 "Ya Muqallibal-qulub, thabbit qalbi 'ala dinik"

 (O Changer of hearts, make my heart firm upon Your religion).

Purpose:

 Scholars recommend reciting this to maintain spiritual discipline and protect the heart from straying.