You wont find प्रज्ञा पारमिता हृदय सूत्र (The Heart Sutra) in Dhammapada. It is not found in any texts of Theravada School of Buddhism.

प्रज्ञा पारमिता हृदय सूत्र is a part of Mahayana School of Buddhism written by either pandit नागार्जुन or by one of his students. By the time प्रज्ञा पारमिता हृदय सूत्र was written Dhammapada probably had already been around for at least 3 hundred years.