"Brethren, my heart's desire and prayer to God for Israel is, that they might be saved" (Romans 10:1). The Apostle Paul did a lot of preaching. He preached in synagogues and in market places, homes and philosophy "lecture halls" (like Mars Hill). But in all the preaching that Paul did, He also prayed.
Prayer in evangelism is important. Prayer acknowledges our weakness and God's power. We cannot control circumstances that advance the Gospel, convict hearts of sin, or bring Gospel realities to bear upon the mind long after the conversation has ended. Indeed, we often struggle with even the most basic matter of speaking up! But God is able to do all the things we cannot and to give us boldness in our work.
Prayer is a means of expressing our burden for souls. In the verse quoted above, Paul connects his "heart's desire" to his prayer to God. The people of Israel were his own countrymen. They were his neighbors and fellow citizens. Paul knew that they had a zeal, but not according to knowledge (Rom. 10:2). His heart was burdened for their salvation and prayer became the means of expressing that burden.
Do you pray for the salvation of the lost? Do you pray for God to work in their lives? Do you pray for your witness to them? Do you pray for God to open doors, give you boldness, and convict their hearts? Do your prayers express your dependence on God and your burden for souls?