These twelve Jesus sent forth, and commanded them, saying, "Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: But go rather to the lost sheep of the house of Israel. And as ye go, preach, saying, The kingdom of heaven is at hand. ... And whosoever shall not receive you, nor hear your words, when ye depart out of that house or city, shake off the dust of your feet. Verily I say unto you, It shall be more tolerable for the land of Sodom and Gomorrha in the day of judgment, than for that city. ... And ye shall be hated of all men for my name's sake: but he that endureth to the end shall be saved. But when they persecute you in this city, flee ye into another: for verily I say unto you, Ye shall not have gone over the cities of Israel, till the Son of man be come."
-- Matthew 10:5ff, 14f., 22f.