Acts 13
49 And the word of the Lord was being spread throughout all the region. 50 But the Jews stirred up the devout and prominent women and the chief men of the city, raised up persecution against Paul and Barnabas, and expelled them from their region. 51 But they shook off the dust from their feet against them, and came to Iconium. 52 And the disciples were filled with joy and with the Holy Spirit.

Mark 6:11
11 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.

This is a sign of a clear conscience. You as the minister of the gospel have done EVERYTHING you can. There is no more that could be done. So you don’t hold a grudge and get angry. You just shake it off and walk away.