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

(1) Allah hath sealed their hearing and their hearts, and on their eyes there is a covering. Theirs will be an awful doom.

(2) In their hearts is a disease, and Allah increaseth their disease. A painful doom is theirs because they lie.

(3) Then, even after that, your hearts were hardened and became as rocks, or worse than rocks, for hardness. For indeed there are rocks from out which rivers gush, and indeed there are rocks which split asunder so that water floweth from them. And indeed there are rocks which fall down for the fear of Allah. Allah is not unaware of what ye do.

(4) And they say: Our hearts are hardened. Nay, but Allah hath cursed them for their unbelief. Little is that which they believe.

(5) And when We made with you a covenant and caused the Mount to tower above you, (saying): Hold fast by that which We have given you, and hear (Our Word), they said: We hear and we rebel. And (worship of) the calf was made to sink into their hearts because of their rejection (of the covenant). Say (unto them): Evil is that which your belief enjoineth on you, if ye are believers.

(6) Say (O Muhammad, to mankind): Who is an enemy to Gabriel! For he it is who hath revealed (this Scripture) to thy heart by Allah's leave, confirming that which was (revealed) before it, and a guidance and glad tidings to believers;

(7) And those who have no knowledge say: Why doth not Allah speak unto us, or some sign come unto us? Even thus, as they now speak, spake those (who were) before them. Their hearts are all alike. We have made clear the revelations for people who are sure.

(8) And of mankind there is he whoso conversation on the life of this world pleaseth thee (Muhammad), and he calleth Allah to witness as to that which is in his heart; yet he is the most rigid of opponents.

(9) Allah will not take you to task for that which is unintentional in your oaths. But He will take you to task for that which your hearts have garnered. Allah is Forgiving, Clement.

(10) And when Abraham said (unto his Lord): My Lord! Show me how Thou givest life to the dead, He said: Dost thou not believe? Abraham said: Yea, but (I ask) in order that my heart may be at ease. (His Lord) said: Take four of the birds and cause them to incline unto thee, then place a part of them on each hill, then call them, they will come to thee in haste, and know that Allah is Mighty, Wise.