The word(s) "heart" appears 171 time(s) in 159 verse(s) in Quran in Muhammad Habib Shakir translation.

(11) And if you are upon a journey and you do not find a scribe, then (there may be) a security taken into possession; but if one of you trusts another, then he who is trusted should deliver his trust, and let him be careful (of his duty to) Allah, his Lord; and do not conceal testimony, and whoever conceals it, his heart is surely sinful; and Allah knows what you do.

(12) He it is Who has revealed the Book to you; some of its verses are decisive, they are the basis of the Book, and others are allegorical; then as for those in whose hearts there is perversity they follow the part of it which is allegorical, seeking to mislead and seeking to give it (their own) interpretation. but none knows its interpretation except Allah, and those who are firmly rooted in knowledge say: We believe in it, it is all from our Lord; and none do mind except those having understanding.

(13) Our Lord! make not our hearts to deviate after Thou hast guided us aright, and grant us from Thee mercy; surely Thou art the most liberal Giver.

(14) Say: Whether you hide what is in your hearts or manifest it, Allah knows it, and He knows whatever is in the heavens and whatever is in the earth, and Allah has power over all things.

(15) And hold fast by the covenant of Allah all together and be not disunited, and remember the favor of Allah on you when you were enemies, then He united your hearts so by His favor you became brethren; and you were on the brink of a pit of fire, then He saved you from it, thus does Allah make clear to you His communications that you may follow the right way.

(16) And Allah did not make it but as good news for you, and that your hearts might be at ease thereby, and victory is only from Allah, the Mighty, the Wise.

(17) And how many a prophet has fought with whom were many worshippers of the Lord; so they did not become weak-hearted on account of what befell them in Allah's way, nor did they weaken, nor did they abase themselves; and Allah loves the patient.

(18) We will cast terror into the hearts of those who disbelieve, because they set up with Allah that for which He has sent down no authority, and their abode is the fire, and evil is the abode of the unjust.

(19) And certainly Allah made good to you His promise when you slew them by His permission, until when you became weak-hearted and disputed about the affair and disobeyed after He had shown you that which you loved; of you were some who desired this world and of you were some who desired the hereafter; then He turned you away from them that He might try you; and He has certainly pardoned you, and Allah is Gracious to the believers.

(20) Then after sorrow He sent down security upon you, a calm coming upon a party of you, and (there was) another party whom their own souls had rendered anxious; they entertained about Allah thoughts of ignorance quite unjustly, saying: We have no hand in the affair. Say: Surely the affair is wholly (in the hands) of Allah. They conceal within their souls what they would not reveal to you. They say: Had we any hand in the affair, we would not have been slain here. Say: Had you remained in your houses, those for whom slaughter was ordained would certainly have gone forth to the places where they would be slain, and that Allah might test what was in your breasts and that He might purge what was in your hearts; and Allah knows what is in the breasts.