Brahms wrote two versions of this choral : this one, with the choral in cantus firmus at the pedal, an another one in the style of an ornated choral. This one's atmosphere is not unlike some piano intermezzi from op. 117, 118 or 119. The theme was also used by Bach (of course), Jean Langlais and surely some other ones.
Dortmundt's 8' foundations work well here.