Ok peeps, START PRAYING!

I'm in the middle of witnessing to a friend of mine down the street. His name is David and he's 12 yrs. old. I won't go into the details but I've been talking to him and showing the gospel to him in the Bible. He agrees with parts of it but just doesn't want to accept Jesus and give his life to Him yet. I know God has already got him thinking but it's very hard for me at this point. He'll seem interested for a little bit but then will take salvation lightly. He at first thought that works saved him. Fortunately God has changed his mind about that, or so he says. It is my will and I'm sure God's that he come to Christ and have his life changed! However I know God is powerful and completely able to do all things, but I truly do not believe that this can be done without prayer. So PLEASE! pray for this him. And also pray for me please that God's will will be done and that He will give me the right words to speak. Please guys! Pray that God will soften David's heart, that he might come to salvation.