Jeremiah 1:5 Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations.
Jeremiah 1:6 Then said I, Ah, Lord God! behold, I cannot speak: for I am a child.
Jeremiah 1:7 But the Lord said unto me, Say not, I am a child: for thou shalt go to all that I shall send thee, and whatsoever I command thee thou shalt speak.
Jeremiah 1:8 Be not afraid of their faces: for I am with thee to deliver thee, saith the Lord.
Jeremiah 1:9 Then the Lord put forth his hand, and touched my mouth. And the Lord said unto me, Behold, I have put my words in thy mouth.
This was the Lord and Jeremiah having a conversation about Jeremiah's ability to do as the Lord commanded.
In verse 5 God is telling Jeremiah exactly who he (Jeremiah) was. God knows us all before we are born, he has plans for our lives before we are born, sometimes we do not live according to God's plan, because God did gave us free choice.
As you can see from verse 6, Jeremiah had doubt about what he could do, and what he couldn't do. He was allowing his flesh to get in the way of what God wanted from him, just like we do today, we think we cannot say something because of who, or what we are.
In verse 7 God is telling Jeremiah what he expected of him I think Jeremiah was afraid of the people, God was telling Jeremiah to go and do what he (God) commanded.
In verse 8 God told him not to be afraid of their faces, because he was with him to deliver him, remember that the Lord will never leave us, nor forsake us, this is what he was saying to Jeremiah. He wanted Jeremiah to know that it didn't matter what the people thought, or said, it only mattered that Jeremiah done as the Lord commanded. Just as Jeremiah was in those days, so should we be today! We need to open our hearts to God, and do as he commands, because he is with us to deliver us.
In verse 9 God put his words into Jeremiah's mouth, I have experienced this, I was afraid to speak God's word to people, but, once I realized that it don't matter what people say, I opened my mouth and God put the words in it, I have said things to people about God that I read in the bible, but if I try to think of something to say from the bible (In the flesh) I really have a hard time thinking of what to say, but if I just open my mouth, God puts the words in it. Read some more about Jeremiah, he done great things in the Lord.