John 16:12-15 (ESV2011)
12 “I still have many things to say to you, but you cannot bear them
now. 13 When the Spirit of truth comes, he will guide you into all the
truth, for he will not speak on his own authority, but whatever he
hears he will speak, and he will declare to you the things that are to
come. 14 He will glorify me, for he will take what is mine and declare
it to you. 15 All that the Father has is mine; therefore I said that
he will take what is mine and declare it to you.
According to v.12, Jesus has more to tell his followers. The Spirit of truth is clearly the Holy Spirit, fully equal in power and majesty to God the father or God the son. Yet the Holy Spirit seems to be a sort of "silent partner", not in the sense that He does not speak, but He "will not speak of Himself". The Holy Spirit will speak the words of Jesus and of Jesus. It is suggested that the Holy Spirit's words will also be from the Father, just as Jesus stated that His words are "from the Father".
Bob Uttley, a Baptist, comments on John chapter 16 at:
"the Spirit of truth" Truth (alētheia) is used in its OT connotation
of trustworthiness and only secondarily in a sense of truthfulness.
Jesus said that He was the truth in John 14:6. This title for the Holy
Spirit emphasizes His role as the revealer of Jesus.
"He will guide you into all the truth"
"for He will not speak on His own initiative, but whatever He hears,
He will speak; and He will disclose to you what is to come" ... The
Spirit will receive truth from the Father, as Jesus did, and pass it
on to believers, as Jesus did.