Often a verse like this is used in connection with missionaries serving the Lord overseas, or ministers preaching the gospel, and we are told to pray for such workers. That is good, but it takes our eye off the full sense of the verse.
But the harvest is hard work. If we are not working for the Lord, if we are not urging ourselves into this work, it is hardly a harvest. The harvest of olden times – before the great harvesting machines were invented – involved much manual labour. Many people were involved, and so it is for us. You are out there all day in the heat of the sun, bending down, doing back-breaking work. There is much lifting and carrying. There is the sense that the crop is safely brought in out of harm’s way. There is the camaraderie of working together, and mutual encouragement, and the rejoicing that comes at the great accomplishment, the sower and the reaper rejoicing together. So too there is much Christian fellowship in bringing in the harvest as fellow-workers.
But the emphasis is on the element of prayer in this second verse. ‘Pray ye therefore the Lord of the harvest’, and we should read it in this sense: that he would both send and bless the work. Both are needed. The seventy were being sent out: they must be those who not only work themselves, but have a deep concern for the entire project, the winning of God’s elect out of a lost world. Their concern is bigger than their own work. They are in sympathy with all the aims of the Lord of the harvest. He is the one who chooses his elect in eternity past, sends his Son into the world to give his life for them, arranges the circumstances of their lives, draws them to himself, pardons their sins, places them among his people, sends teachers to them, sanctifies them, and gathers them safely into his heavenly barn at the end of life.
How amazing that God has in part made the success of the harvest dependent on our prayers! It is a further privilege given to God’s people; it is his drawing us close to him as fellow workers, and giving us a part with him in his work and that we do not deserve.