What appears to be the same incident is recorded in Luke 9.
Luke 9:1 Then he called his twelve disciples together, and
gave them power and authority over all devils, and to cure diseases.
Luke 9:2 And he sent them to preach the kingdom of God, and to heal the sick.
Luke 9:3 And he said unto them, Take nothing for your journey, neither staves, nor scrip, neither bread, neither money; neither have two coats apiece.
Luke 9:4 And whatsoever house ye enter into, there abide, and thence depart.
Luke 9:5 And whosoever will not receive you, when ye go out of that city, shake off the very dust from your feet for a testimony against them.
Luke 9:6 And they departed, and went through the towns, preaching the gospel, and healing every where.
Notice,it appears Jesus did not go with them:
Luke 9:10 And the apostles,
when they were returned, told him all that they had done. And he took them, and went aside privately into a desert place belonging to the city called Bethsaida.
Compare:
Matthew 10:1 And when he had called unto him his twelve disciples, he gave them power against unclean spirits, to cast them out, and to heal all manner of sickness and all manner of disease.
Matthew 10:2 Now the names of the twelve apostles are these; The first, Simon, who is called Peter, and Andrew his brother; James the son of Zebedee, and John his brother;
Matthew 10:3 Philip, and Bartholomew; Thomas, and Matthew the publican; James the son of Alphaeus, and Lebbaeus, whose surname was Thaddaeus;
Matthew 10:4 Simon the Canaanite, and Judas Iscariot, who also betrayed him.
Matthew 10:5 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:
Matthew 10:6 But go rather to the lost sheep of the house of Israel.
Matthew 10:7 And as ye go, preach, saying, The kingdom of heaven is at hand.
Matthew 10:8 Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give.
Matthew 10:9 Provide neither gold, nor silver, nor brass in your purses,
Matthew 10:10 Nor scrip for your journey, neither two coats, neither shoes, nor yet staves: for the workman is worthy of his meat.
Matthew 10:11 And into whatsoever city or town ye shall enter, enquire who in it is worthy; and there abide till ye go thence.
Matthew 10:12 And when ye come into an house, salute it.
Matthew 10:13 And if the house be worthy, let your peace come upon it: but if it be not worthy, let your peace return to you.
Matthew 10:14 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.
Luke's account offers a solution which explains the phrase:
"..before the Son of Man comes."
Luke 10:1 After these things the Lord appointed other seventy also, and sent them two and two before his face into every city and place,
whither he himself would come.