In verse 29 the focus of the gathering shifted from the New World and this branch of the House of Israel back to the Old World House of Israel. The covenant promises will be kept to both branches, but this will require that the Old World House of Israel accept the gospel of the Savior. Thus it will be preached to them, and they will believe in Jesus Christ as the Son of God. The witness of their understanding will be that they “shall pray unto the Father in my name.”
The Jews certainly pray to the Father. That will be nothing new for them. They believe in the Father. The difference is that they will understand the mission of the Atoning Messiah and accept him as the mediator between man and God. Thus it is significant that they would pray “unto the Father in my name.”