The word(s) "heart" appears 169 time(s) in 159 verse(s) in Quran in Muhammad Pickthal translation.

(21) Assuredly ye will be tried in your property and in your persons, and ye will hear much wrong from those who were given the Scripture before you, and from the idolaters. But if ye persevere and ward off (evil), then that is of the steadfast heart of things.

(22) Those are they, the secrets of whose hearts Allah knoweth. So oppose them and admonish them, and address them in plain terms about their souls.

(23) Except those who seek refuge with a people between whom and you there is a covenant, or (those who) come unto you because their hearts forbid them to make war on you or make war on their own folk. Had Allah willed He could have given them power over you so that assuredly they would have fought you. So, if they hold aloof from you and wage not war against you and offer you peace, Allah alloweth you no way against them.

(24) Then because of their breaking of their covenant, and their disbelieving in the revelations of Allah, and their slaying of the prophets wrongfully, and their saying: Our hearts are hardened - Nay, but Allah set a seal upon them for their disbelief, so that they believe not save a few -

(25) And because of their breaking their covenant, We have cursed them and made hard their hearts. They change words from their context and forget a part of that whereof they were admonished. Thou wilt not cease to discover treachery from all save a few of them. But bear with them and pardon them. Lo! Allah loveth the kindly.

(26) O Messenger! Let not them grieve thee who vie one with another in the race to disbelief, of such as say with their mouths: "We believe," but their hearts believe not, and of the Jews: listeners for the sake of falsehood, listeners on behalf of other folk who come not unto thee, changing words from their context and saying: If this be given unto you, receive it, but if this be not given unto you, then beware! He whom Allah doometh unto sin, thou (by thine efforts) wilt avail him naught against Allah. Those are they for whom the Will of Allah is that He cleanse not their hearts. Theirs in the world will be ignominy, and in the Hereafter an awful doom;

(27) And thou seest those in whose heart is a disease race toward them, saying: We fear lest a change of fortune befall us. And it may happen that Allah will vouchsafe (unto thee) the victory, or a commandment from His presence. Then will they repent them of their secret thoughts.

(28) (They said:) We wish to eat thereof, that we may satisfy our hearts and know that thou hast spoken truth to us, and that thereof we may be witnesses.

(29) Of them are some who listen unto thee, but We have placed upon their hearts veils, lest they should understand, and in their ears a deafness. If they saw every token they would not believe therein; to the point that, when they come unto thee to argue with thee, the disbelievers say: This is naught else than fables of the men of old.

(30) If only, when Our disaster came on them, they had been humble! But their hearts were hardened and the devil made all that they used to do seem fair unto them!