The word(s) "heart" appears 161 time(s) in 147 verse(s) in Quran in Mohsin Khan translation.

(11) It is He Who has sent down to you (Muhammad صلى الله عليه وسلم) the Book (this Qur'an). In it are Verses that are entirely clear, they are the foundations of the Book [and those are the Verses of Al-Ahkam (commandments), Al-Fara'id (obligatory duties) and Al-Hudud (legal laws for the punishment of thieves, adulterers)]; and others not entirely clear. So as for those in whose hearts there is a deviation (from the truth) they follow that which is not entirely clear thereof, seeking Al-Fitnah (polytheism and trials), and seeking for its hidden meanings, but none knows its hidden meanings save Allah. And those who are firmly grounded in knowledge say: "We believe in it; the whole of it (clear and unclear Verses) are from our Lord." And none receive admonition except men of understanding. (Tafsir At-Tabari).

(12) (They say): "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."

(13) Verily, those who disbelieved after their Belief and then went on increasing in their disbelief (i.e. disbelief in the Qur'an and in Prophet Muhammad صلى الله عليه وسلم) - never will their repentance be accepted [because they repent only by their tongues and not from their hearts]. And they are those who are astray.

(14) And hold fast, all of you together, to the Rope of Allah (i.e. this Qur'an), and be not divided among yourselves , and remember Allah's Favour on you, for you were enemies one to another but He joined your hearts together, so that, by His Grace, you became brethren (in Islamic Faith), and you were on the brink of a pit of Fire, and He saved you from it. Thus Allah makes His Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.,) clear to you, that you may be guided.

(15) When two parties from among you were about to lose heart, but Allah was their Wali (Supporter and Protector). And in Allah should the believers put their trust.

(16) Allah made it not but as a message of good news for you and as an assurance to your hearts. And there is no victory except from Allah, the All-Mighty, the All-Wise.

(17) And many a Prophet (i.e. many from amongst the Prophets) fought (in Allah's Cause) and along with him (fought) large bands of religious learned men. But they never lost heart for that which did befall them in Allah's Way, nor did they weaken nor degrade themselves. And Allah loves As-Sabirun (the patient).

(18) We shall cast terror into the hearts of those who disbelieve, because they joined others in worship with Allah, for which He had sent no authority; their abode will be the Fire and how evil is the abode of the Zalimun (polytheists and wrong-doers).

(19) Then after the distress, He sent down security for you. Slumber overtook a party of you, while another party was thinking about themselves (as how to save their ownselves, ignoring the others and the Prophet صلى الله عليه وسلم) and thought wrongly of Allah - the thought of ignorance. They said, "Have we any part in the affair?" Say (O Muhammad صلى الله عليه وسلم): "Indeed the affair belongs wholly to Allah." They hide within themselves what they dare not reveal to you, saying: "If we had anything to do with the affair, none of us would have been killed here." Say: "Even if you had remained in your homes, those for whom death was decreed would certainly have gone forth to the place of their death," but that Allah might test what is in your breasts; and to purify that which was in your hearts (sins), and Allah is All-Knower of what is in (your) breasts.

(20) O you who believe! Be not like those who disbelieve (hypocrites) and who say to their brethren when they travel through the earth or go out to fight: "If they had stayed with us, they would not have died or been killed," so that Allah may make it a cause of regret in their hearts. It is Allah that gives life and causes death. And Allah is All-Seer of what you do.