Gregory the Great
Catena Aurea · Lukasevangelium 10
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. Therefore said he unto them, The harvest truly is great, but the labourers are few: pray ye therefore the Lord of the harvest, that he would send forth labourers into his harvest. It follows, And he sent them two and two.
(ubi sup.) Hereby also the people must be induced to pray for their pastors, that they may he able to work what is good for them, and that their tongue grow not lifeless in exhortation. For often for their own wickedness their tongue is tied. But often for the fault of the people it comes to pass that the word of preaching is withdrawn from their rulers.