un-wosh'-'-n (aniptos): Occurs only twice in the New Testament, not at all in the Hebrew or Greek Old Testament (Mt 15:20 = Mr 7:2). Jesus is here denouncing the traditionalism of the scribes and Pharisees. Uncleanness, to them, was external and purification was ceremonial. Hence, the Pharisaic view that the hands became unclean (religiously, not physically), and so before meals must be cleansed (religiously) by washing, which consisted in two affusions and must extend up to the wrist, else the hand was still unclean. Jewish tradition traced this custom back to Solomon (see Shabbath 14b, end), but the first unmistakable occurrence of the custom is in the Sibylline Oracles (3:591-93), where the hands are said to be washed in connection with prayer and thanksgiving. The schools of Shammai and Hillel, though usually differing on points of tradition, agreed on the washing of hands as necessary for ceremonial purification (having reached this agreement in the early part of Jesus' life).
Broadus, Commentary on Matthew (15:2-20); Gould, Swete, commentaries on Mark (7:2); Edersheim, The Life and Times of Jesus the Messiah, II, 8 ff; Schurer. HJP, div II, volume I, section 25 (" Scribism").
Charles B. Williams