John Calvin Commentary Matthew 9:38

"Pray ye therefore the Lord of the harvest, that he send forth laborers into his harvest." — Matthew 9:38 (ASV)

Pray therefore to the Lord of the harvest. Since no one by themselves will become a sincere and faithful minister of the gospel, and since no one properly discharges the office of teacher except those whom the Lord raises up and endows with the gifts of His Spirit, whenever we observe a scarcity of pastors, we must lift our eyes to Him to provide the remedy. There never was greater necessity for offering this prayer than during the fearful desolation of the church which we now see everywhere around us.