The word(s) "hearts" appears 159 time(s) in 147 verse(s) in Quran in Abdullah Yusuf Ali translation.

(81) That He may make the suggestions thrown in by Satan, but a trial for those in whose hearts is a disease and who are hardened of heart: verily the wrong-doers are in a schism far (from the Truth):

(82) And that those on whom knowledge has been bestowed may learn that the (Qur'an) is the Truth from thy Lord, and that they may believe therein, and their hearts may be made humbly (open) to it: for verily Allah is the Guide of those who believe, to the Straight Way.

(83) And those who dispense their charity with their hearts full of fear, because they will return to their Lord;-

(84) But their hearts are in confused ignorance of this; and there are, besides that, deeds of theirs, which they will (continue) to do,-

(85) By men whom neither traffic nor merchandise can divert from the Remembrance of Allah, nor from regular Prayer, nor from the practice of regular Charity: Their (only) fear is for the Day when hearts and eyes will be transformed (in a world wholly new),-

(86) Is it that there is a disease in their hearts? or do they doubt, or are they in fear, that Allah and His Messenger will deal unjustly with them? Nay, it is they themselves who do wrong.

(87) Thus have We caused it to enter the hearts of the sinners.

(88) And verily thy Lord knoweth all that their hearts do hide. As well as all that they reveal.

(89) And thy Lord knows all that their hearts conceal and all that they reveal.

(90) Then there are among men such as say, "We believe in Allah"; but when they suffer affliction in (the cause of) Allah, they treat men's oppression as if it were the Wrath of Allah! And if help comes (to thee) from thy Lord, they are sure to say, "We have (always) been with you!" Does not Allah know best all that is in the hearts of all creation?