Deuteronomy 21:6

Wash. This was intended to testify that they were not guilty of the blood which had been shed, and that they wished to remove the punishment of it from themselves upon the head of the heifer, (Calmet) the representative of the unknown murderer. So Pilate conformed to this custom, when he condemned Christ on the bare accusation of the Jews; (Matthew xxvii. 24) and the priest, at mass, washes his hands, as an emblem of that innocence, with which he ought to approach the holy of holies. (Haydock) --- Asterius was stricken with lightning, for touching the altar of Jupiter without having washed his hands. (Natal. Myth. i. 10. 14.) The pagans generally purified themselves with fumigations, or by sprinkling sea water upon their bodies. Achilles ordered the things which had been used to purify the Greeks, at the siege of Troy, to be thrown into the sea, as being unclean. (Iliad i.)