They try to box me in like Cassius Clay
Hey I'm like Muhammad when he fasted
Cassius Clay —> Muhammad Ali
Muhammad Ali changed his name when he converted to the Nation of Islam, which holds fasting (during the month of Ramadan) as one of its central pillars. Common is letting those who limit our doubt him know that he has the focus of a heavyweight champion (i.e. Ali).
(Also, notice the wordplay on “box me in”.)
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