That was in 1928.
Davis retired in 1984, but the group – one of the greatest black gospel groups of all time, if not the greatest – continues. (Some of the other greats, like the Swan Silvertones' Claude Jeter, actually got their start in the Dixie Hummingbirds.)
Most folks know the group's work from Paul Simon's 1973 "Loves Me Like a Rock." I prefer "Christian Automobile."1