The Holy Spirit
Romans 8:26
Likewise the Spirit also helps in our weaknesses. For we do not know what we should pray for as we ought, but the Spirit Himself makes intercession for us with groanings which cannot be uttered.

John 16:13-14
However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come.  He will glorify Me, for He will take of what is Mine and declare it to you.

John 14:26
But the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you.

Zechariah 4:6b
‘Not by might nor by power, but by My Spirit,’ says the LORD of hosts.