Ref Rev:1 God speaking to us by His Son as in all things from the Father through the Son, which includes the gift of the Spirit in us.Yes, His Holy Spirit, NOT a third God being as the Trinity teach.
David has spoken about Jesus. Jesus has tell them that David has spoken about Him. It was Jesus was with Abraham before he destroyed Sodom and Gomorrah.
Read Revelation 1:1-8. Who is talking with John?
It was Jesus Himself. And the Holy Spirit is Jesus Himself by His power speaking to us. Not another being.
Father=>Son=>church