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

(31) And of them there are some who listen to you; but We have set veils on their hearts, so they understand it not, and deafness in their ears; and even if they see every one of the Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) they will not believe therein; to the point that when they come to you to argue with you, the disbelievers say: "These are nothing but tales of the men of old."

(32) When Our Torment reached them, why then did they not humble themselves (believe with humility)? But their hearts became hardened, and Shaitan (Satan) made fair-seeming to them that which they used to do.

(33) Say (to the disbelievers): "Tell me, if Allah took away your hearing and your sight, and sealed up your hearts, who is there - an ilah (a god) other than Allah who could restore them to you?" See how variously We explain the Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.), yet they turn aside.

(34) And We shall turn their hearts and their eyes away (from guidance), as they refused to believe therein for the first time, and We shall leave them in their trespass to wander blindly.

(35) (And this is in order) that the hearts of those who disbelieve in the Hereafter may incline to such (deceit), and that they may remain pleased with it, and that they may commit what they are committing (all kinds of sins and evil deeds).

(36) Is it not clear to those who inherit the earth in succession from its (previous) possessors, that had We willed, We would have punished them for their sins. And We seal up their hearts so that they hear not?

(37) Those were the towns whose story We relate unto you (O Muhammad صلى الله عليه وسلم). And there came indeed to them their Messengers with clear proofs, but they were not such as to believe in that which they had rejected before. Thus Allah does seal up the hearts of the disbelievers (from every kind of religious guidance).

(38) And surely, We have created many of the jinn and mankind for Hell. They have hearts wherewith they understand not, and they have eyes wherewith they see not, and they have ears wherewith they hear not (the truth). They are like cattle, nay even more astray; those! They are the heedless ones.

(39) The believers are only those who, when Allah is mentioned, feel a fear in their hearts and when His Verses (this Qur'an) are recited unto them, they (i.e. the Verses) increase their Faith; and they put their trust in their Lord (Alone);

(40) Allah made it only as glad tidings, and that your hearts be at rest therewith. And there is no victory except from Allah. Verily, Allah is All-Mighty, All-Wise.