The word(s) "hearts" appears 136 time(s) in 127 verse(s) in Quran in Muhammad Habib Shakir translation.

(21) But on account of their breaking their covenant We cursed them and made their hearts hard; they altered the words from their places and they neglected a portion of what they were reminded of; and you shall always discover treachery in them excepting a few of them; so pardon them and turn away; surely Allah loves those who do good (to others).

(22) O Apostle! let not those grieve you who strive together in hastening to unbelief from among those who say with their mouths: We believe, and their hearts do not believe, and from among those who are Jews; they are listeners for the sake of a lie, listeners for another people who have not come to you; they alter the words from their places, saying: If you are given this, take it, and if you are not given this, be cautious; and as for him whose temptation Allah desires, you cannot control anything for him with Allah. Those are they for whom Allah does not desire that He should purify their hearts; they shall have disgrace in this world, and they shall have a grievous chastisement in the hereafter.

(23) But you will see those in whose hearts is a disease hastening towards them, saying: We fear lest a calamity should befall us; but it may be that Allah will bring the victory or a punishment from Himself, so that they shall be regretting on account of what they hid in their souls.

(24) They said: We desire that we should eat of it and that our hearts should be at rest, and that we may know that you have indeed spoken the truth to us and that we may be of the witnesses to it.

(25) And of them is he who hearkens to you, and We have cast veils over their hearts lest they understand it and a heaviness into their ears; and even if they see every sign they will not believe in it; so much so that when they come to you they only dispute with you; those who disbelieve say: This is naught but the stories of the ancients.

(26) Yet why did they not, when Our punishment came to them, humble themselves? But their hearts hardened and the Shaitan made what they did fair-seeming to them.

(27) Say: Have you considered that if Allah takes away your hearing and your sight and sets a seal on your hearts, who is the god besides Allah that can bring it to you? See how We repeat the communications, yet they turn away.

(28) And We will turn their hearts and their sights, even as they did not believe in it the first time, and We will leave them in their inordinacy, blindly wandering on.

(29) And that the hearts of those who do not believe in the hereafter may incline to it and that they may be well pleased with it and that they may earn what they are going to earn (of evil).

(30) Is it not clear to those who inherit the earth after its (former) residents that if We please We would afflict them on account of their faults and set a seal on their hearts so they would not hear.