3 verses have
heart
in Edition Clear Qur'an by Talal Itani / Al-Kahf (The Cave)

18:14And We strengthened their hearts, when they stood up and said, “Our Lord is the Lord of the heavens and the earth; we will not call on any god besides Him, for then we would have spoken an outrage.”

18:28And content yourself with those who pray to their Lord morning and evening, desiring His Presence. And do not turn your eyes away from them, desiring the glitter of this world. And do not obey him whose heart We have made heedless of Our remembrance—so he follows his own desires—and his priorities are confused.

18:57Who does greater wrong than he, who, when reminded of his Lord’s revelations, turns away from them, and forgets what his hands have put forward? We have placed coverings over their hearts, lest they understand it, and heaviness in their ears. And if you call them to guidance, they will not be guided, ever.