Why the heart?
The heart is the primary receiver of Divine Revelation. The Quran mentions the heart over 140 times, describing its various states and its central role in our lives. Allah ﷻ reveals that the Qur'an was sent down specifically upon the heart of the Prophet ﷺ.
Surah ash-Shu'ara (26:193-195) "The Trustworthy Spirit has brought it down upon your heart [Prophet], so that you could bring warning in a clear Arabic tongue."
This teaches us that the heart, more than the ears or the eyes, is the true vessel for guidance.