Sorry all this about hygiene and hand-washing that religions - in this case, Judaism, Christianity and Islam - like to take credits for being the first seemed awfully trivial.
Sorry but all three lost the contest, to an even older culture and religion.
According to the Sumerian poem, titled today as the Death of Bilgames - which Bilgames or Gilgames being the Sumerian name for Gilgamesh.
Anyway, in this text, the ritual of hand washing was supposedly lost in Sumer, but after Bilgames met Ziusudra, the Sumerian hero of the Flood, Bilgames brought back the custom of hand washing to Uruk.
Source:
Death of Gilgamesh, translation from Electronic Text Corpus of Sumerian Literature, Oxford University.
Later versions of the Gilgamesh myth, from the Akkadian, Babylonian and Assyrian of the Epic, don’t include this hand washing ritual, but the oldest Gilgamesh-Ziusudra myth do have it.
Sorry, but the whole hand washing custom is not original idea of the Abrahamic religions.