Pleading in behalf of one to another--such as Jesus speaking in our favor to God; or the Holy Spirit praying for us when we don't know what to pray; or believers praying for one another...

It it Christ that died, yea rather, is risen again, who is even at the right hand of God, who also maketh intercession for us.
Romans 8:34

Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered.
Romans 8:26

See also Paul's prayer for all the believeers in: Ephesians 3:14-21