Luke 10:1,2

After these things the Lord appointed— The scene of Christ's ministry being from this time forth to lie in Judea, and the country beyond Jordan, it was expedient that his way should be prepared in every city and village of those countries whither he was to come: he therefore sent out seventy of his disciples on this work, mentioning the particular places whichhe intended to visit, and in which they were to preach; whereas the twelve had been allowed to go where they pleased, provided theyconfined their ministry to the lost sheep of the house of Israel. St. Luke is the only evangelist who has given us this account of Christ's sending out the seventy; and it is the less to be wondered at, that he should do it so particularly, if the ancient tradition be true, which is generally believed, that he himself was one of the number. It is remarkable, that our Lord assigns the same reason for the mission of the seventy, which he had assigned for the mission of the twelve disciples. The harvest was plenteous in Judea and Peraea, as well as in Galilee, and the labourers there also were few. See Matthew 9:37.