Our Lord! Let Not Our Hearts Deviate (from the truth) After You Have Guided Us

رَبَّنَا لاَ تُزِغْ قُلُوبَنَا بَعْدَ إِذْ هَدَيْتَنَا

(Our Lord! Let not our hearts deviate (from the truth) after You have guided us.) meaning, “Do not deviate our hearts from the guidance after You allowed them to acquire it. Do not make us like those who have wickedness in their hearts, those who follow the Mutashabih in the Qur’an. Rather, make us remain firmly on Your straight path and true religion.”

وَهَبْ لَنَا مِن لَّدُنكَ

(And grant us from Ladunka) meaning, from You,

رَحْمَةً

(Mercy) with which You make our hearts firm, and increase in our Faith and certainty,

إِنَّكَ أَنتَ الْوَهَّابُ

Truly, You are the Bestower
Ibn Abi Hatim and Ibn Jarir recorded that Umm Salamah said that the Prophet used to supplicate,

يَا مُقَلِّبَ الْقُلُوبِ ثَبِّتْ قَلْبِي عَلَى دِينِك

He then recited,

رَبَّنَا لاَ تُزِغْ قُلُوبَنَا بَعْدَ إِذْ هَدَيْتَنَا وَهَبْ لَنَا مِن لَّدُنكَ رَحْمَةً إِنَّكَ أَنتَ الْوَهَّابُ

“Our Lord! Let not our hearts deviate (from the truth) after You have guided us, and grant us mercy from You. Truly, You are the Bestower.” Surah Al-i-Imran [3:8]
Source: Tafsir Ibn Kathir