Hill looks back on his time in the Duke Ellington-Cotton Club musical on Broadway.
The pop singer crooned "Hallelujah" for a lucky After Midnight crowd.
The civil rights activist visited the cast and saw the acclaimed show at the Brooks Atkinson Theatre.
Lang's opening night as the musical's latest Special Guest Star took place on February 11.
Guests also included Wynton Marsalis, k.d. lang, and Darlene Love.