John Gill Commentary Luke 9:5

"And as many as receive you not, when ye depart from that city, shake off the dust from your feet for a testimony against them." — Luke 9:5 (ASV)

And whosoever will not receive you
to their houses:

when you go out of the city ;
where lodging and entertainment are refused you;

shake off the very dust from your feet, for a testimony against them ;
(See Gill on Matthew 10:14) (See Gill on Mark 6:11)