Wesley did, in fact, say: "Cleanliness is indeed next to godliness", which would suggest someone had said as much earlier. Perhaps it was this: "For cleanness of body was ever esteemed to proceed from a due reverence to God, to society, and to ourselves." That comes from Francis Bacon's 'Advancement of Learning' published in 1605. It seems to say very much the same thing. I hope that's the one you're after, Dr S, though Wesley was almost certainly the first to express the idea in the words you originally offered. Cheers