Protest against those unwilling to hear the Gospel
Matthew 10:14 (ASV 1901)
14And whosoever shall not receive you, nor hear your words, as ye go forth out of that house or that city, shake off the dust of your feet.
Mark 6:11 (ASV 1901)
11And whatsoever place shall not receive you, and they hear you not, as ye go forth thence, shake off the dust that is under your feet for a testimony unto them.
Luke 9:5 (ASV 1901)
5And as many as receive you not, when ye depart from that city, shake off the dust from your feet for a testimony against them.