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

(41) When He made the slumber fall upon you as a reassurance from him and sent down water from the sky upon you, that thereby He might purify you, and remove from you the fear of Satan, and make strong your hearts and firm (your) feet thereby.

(42) When thy Lord inspired the angels, (saying): I am with you. So make those who believe stand firm. I will throw fear into the hearts of those who disbelieve. Then smite the necks and smite of them each finger.

(43) O ye who believe! Obey Allah, and the messenger when He calleth you to that which quickeneth you, and know that Allah cometh in between the man and his own heart, and that He it is unto Whom ye will be gathered.

(44) When the hypocrites and those in whose hearts is a disease said: Their religion hath deluded these. Whoso putteth his trust in Allah (will find that) lo! Allah is Mighty, Wise.

(45) That is because Allah never changeth the grace He hath bestowed on any people until they first change that which is in their hearts, and (that is) because Allah is Hearer, Knower.

(46) And (as for the believers) hath attuned their hearts. If thou hadst spent all that is in the earth thou couldst not have attuned their hearts, but Allah hath attuned them. Lo! He is Mighty, Wise.

(47) O Prophet! Say unto those captives who are in your hands: If Allah knoweth any good in your hearts He will give you better than that which hath been taken from you, and will forgive you. Lo! Allah is Forgiving, Merciful.

(48) How (can there be any treaty for the others) when, if they have the upper hand of you, they regard not pact nor honour in respect of you? They satisfy you with their mouths the while their hearts refuse. And most of them are wrongdoers.

(49) And He will remove the anger of their hearts. Allah relenteth toward whom He will. Allah is Knower, Wise.

(50) They alone ask leave of thee who believe not in Allah and the Last Day, and whose hearts feel doubt, so in their doubt they waver.