Is supplication by the heart considered and counted?

The thoughts that cross one's mind are not held against a person by Islamic law, unless they are uttered or acted upon. As for supplication (du'a) made solely with the heart without the tongue, there is no explicit textual evidence for it. However, it can be analogized to remembrance (dhikr) made with the heart, which is counted for the person, as stated in the Qudsi Hadith: "If he remembers Me to himself, I remember him to Myself." The essence of supplication originates from the heart, and the tongue is a تابع (subordinate) to it. Uttering it aloud is preferable because it involves the congruence of both the heart and the tongue.