And whosoever shall not receive you, nor hear you, when ye depart thence, shake off the dust under your feet for a testimony against them. -Mark 6:11
For Jews to shake dust off their feet was a sign that Gentile territory was unclean. In the New Testament this action indicates that those who have rejected the gospel have made themselves as Gentiles and must face the judgment of God. (See also Acts 13:51) To sprinkle dust on the head was a sign of mourning (Joshua 7:6), and to sit in dust denotes extreme affliction (Isaiah 47:1). “Dust” is used to denote the grave (Job 7:21). To lick the dust is a sign of abject submission (Psalms 72:9); and to throw dust at someone is a sign of abhorrence (2 Samuel 16:13; Acts 22:23). To bite the dust is to suffer a defeat. It became a common expression through its use in American movies about the early west.
Given the many B-feature cowboy movies in which the bad guys, or occasionally the pesky redskins, would ‘bite the dust’, we might expect this to be of American origin. It isn’t though. The same notion is expressed in the earlier phrase ‘lick the dust’, from the Bible, where there are several uses of it, including Psalms 72:9 “They that dwell in the wilderness shall bow before him; and his enemies shall lick the dust.”