See these verses fully explained in the notes at Matthew 10:9-15. In Matthew 10:5 they were commanded not to go among the Gentiles or Samaritans. Mark omits that direction, perhaps, because he was writing for the “Gentiles,” and the direction might create unnecessary difficulty or offence. Perhaps he omits it also because the command was given for a temporary purpose, and was not in force at the time of his writing.
Related Commentaries of Mark 6:8
Mark 6:8-11
8 And commanded them that they should take nothing for their journey, save a staff only; no scrip, no bread, no moneyb in their purse:
9 But be shod with sandals; and not put on two coats.
10 And he said unto them,In what place soever ye enter into an house, there abide till ye depart from that place.
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. Verily I say unto you, It shall be more tolerable for Sodom andc Gomorrha in the day of judgment, than for that city.