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

(141) And whether ye hide your word or publish it, He certainly has (full) knowledge, of the secrets of (all) hearts.

(142) And We have set none but angels as Guardians of the Fire; and We have fixed their number only as a trial for Unbelievers,- in order that the People of the Book may arrive at certainty, and the Believers may increase in Faith,- and that no doubts may be left for the People of the Book and the Believers, and that those in whose hearts is a disease and the Unbelievers may say, "What symbol doth Allah intend by this?" Thus doth Allah leave to stray whom He pleaseth, and guide whom He pleaseth: and none can know the forces of thy Lord, except He and this is no other than a warning to mankind.

(143) hearts that Day will be in agitation;

(144) By no means! but on their hearts is the stain of the (ill) which they do!

(145) And glorify the name of their Guardian-Lord, and (lift their hearts) in prayer.

(146) The which doth mount (Right) to the hearts:

(147) (The same) who whispers into the hearts of Mankind,-