I prayed for freedom for twenty years, but received no answer until I prayed with my legs.

Douglass - prayed with my legs - wist_info quote

Frederick Douglass (1817-1895) American abolitionist, orator, writer
(Attributed)

Mentioned frequently as being part of his earlier speeches, but unsourced. Also found as "failed to see the slightest scintillation of an answer until I prayed with my legs."