John 15:26
When the Advocate comes, whom I will send to you from the Father, the Spirit of truth who comes from the Father, he will testify on my behalf — the Paraclete is introduced as a legal witness (martyreō—testify, bear witness). The Spirit comes from the Father, is sent by Jesus, and testifies to Jesus; this intricate Trinitarian relationship shows that all three are united in the work of witness. The Spirit of truth bears witness to the Truth himself, Jesus Christ.