Middlesex 235BisII, Political and Social Series (Dalton & Hamer, page 542)

Denomination: penny
235BisII. O: Chained Negro in supplication. AM I NOT A MAN AND A BROTHER.
             The legend in smaller letters. As No. 235.
          R: WHATSOEVER | YE WOULD THAT | MEN SHOULD DO | TO YOU, DO YE |
             EVEN SO TO | THEM. Similar to No. 235, but no period after M.

In Addenda, page 542.

Keywords

am i not a man and a brother,whatsoever ye would that men should do to you do ye even so to them