Lk 24:45-47, Mt 28:19-20, Mk 16:15, Acts 1:8
In the Old Testament, David proclaimed God's salvation to many people. (Psalms 40:9-10)
Psalms 40:9 I have preached righteousness in the great congregation: lo, I have not refrained my lips, O Lord, thou knowest. 10 I have not hid thy righteousness within my heart; I have declared thy faithfulness and thy salvation: I have not concealed thy lovingkindness and thy truth from the great congregation.
Jesus made known to his disciples that it was recorded in the Old Testament that repentance for the forgiveness of sins in his name was preached to all nations, starting from Jerusalem. (Luke 24:45-47)
Luke 24:45 Then opened he their understanding, that they might understand the scriptures, 46 And said unto them, Thus it is written, and thus it behooved Christ to suffer, and to rise from the dead the third day: 47 And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.
Jesus commanded us to preach to all nations that Jesus is the Christ. (Mt 28:19-20, Mark 16:15, Acts 1:8)
Mt 28:19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: 20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.
Mark 16:15 And he said unto them, Go ye into all the world, and preach the gospel to every creature.
Acts 1:8 But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth.