How do we know that Jesus speaks the words of God?

John 3:34 affirms that 'for whom God hath sent speaketh the words of God: for God giveth not the Spirit by measure unto him.' This indicates that Jesus, being sent by God, communicates divine truth. His testimony is validated by the fullness of the Holy Spirit He received, empowering Him to teach and act with divine authority. Moreover, His words are accompanied by signs and wonders that confirm His identity and authority, proving that He is indeed the embodiment of God's revelation to humanity.