“Therefore pray the Lord of the harvest to send out labourers into His harvest.”
Question: How to grow into that kind of prayer?

Verses 36-37 give context, “But when He saw the multitudes, He was moved with compassion for them, because they were weary and scattered, like sheep having no shepherd. Then He said to His disciples, ‘The harvest truly is plentiful, but the labourers are few.“

When to speak?

The Holy Spirit will guide us to discern when to speak.

Personal

Bruce is a fellow member of my international bible study group. He is in his nineties, and had always been a member of a church with a main focus on current social issues. He regards his conversion time as being only a few years ago, when he was given a close conviction of sin and repentance, when Jesus’ gift of salvation became personal, leading to a personal relationship with God in Jesus, and he began to earnestly read the bible and begin bible study to see what it really means.
When we enter into that close relationship of faith in Jesus, His Holy Spirit lives in us. He makes us less self-concerned, and more open to knowing His will for us.
Bruce approached his neighbours in the condominium where he and his wife live, to start an informal bible study group of about a dozen people, and he has now been leading that group for a couple of years.

General

We can also be guided to make a general proclamation.
Many years ago, a friend from church had been a truck driver before retiring, and he had been surprised one day when a car came beside him and the young man driving gestured to him to pull over — this was in the days before our current road rage. Although he was worried about this, he stopped and the man approached him in an agitated state. But the young man began asking him, “Is that true? What your bumper sticker says – Does Jesus really love me?”

Our greatest need

There are so many people out there who haven’t heard the gospel, the field is indeed ripe for all to hear.
In our verse, Jesus had compassion for the multitudes, not primarily because of injustice under Roman rule, but because they were like sheep without a shepherd. Being disconnected from God left them without hope, and led them into all sorts of calamities, as a consequence of our human condition of sin.

My prayer is for God’s guidance in being given the things to do, and the words to say, to the people He brings into my life. And that I will always remember that without the gospel they are lost like sheep without a shepherd. May I share Jesus’ compassion on them and their need to hear and understand the gospel.