It is narrated from Hazrat Abu Musa (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: The heart is called "qalb" because it keeps turning, and the example of the heart is like that of a feather at the root of a tree which the wind keeps turning over and over.
Hadith Referenceمسند احمد / تتمہ مُسْنَدِ الْكُوفِيِّينَ / 19757
Hadith Gradingحکم دارالسلام:إسناده ضعيف، وقد اختلف فى رفعه ووقفه، ووقفه أرجح يزيد بن سمع من الجريري بعد الاختلاط