These were the words of Christ to His disciples before His suffering. It was no doubt that they were troubled! The Lord was giving to leave them! The Lord however wants them to focus on His return! It was "expedient" for Him to go!
Who: " I will pray that Father for the Holy Spirit" Christ speaks to them as the victory and risen Lord. The Conqueror...though He faced suffering and the burden of the cross. How could He pray so boldly? As the victor of all things and one enthroned in glory, He would request a comforter for His church in His absence. One in whom He would abide in. The paracleat! A comforter leaves in limited fashion but returns in UNLIMITED fashion! He is the Spirit of Truth! "He will testify of Me" says Christ. One who is self effacing and does not "toot His own horn." And what God speaks the Holy Spirit reiterates!
How: A comforter that He sends to us. If you think back on Pentecost you remember that the harvest of the first fruits symbolizes the whole harvest. There was 1. The sound of a mighty, rushing wind. You cannot see the Holy Spirit but can see His work and effect! He testifies of Jesus Christ! This is one of the most important things to remember. It is ALWAYS Christ and Him crucified! It was redemption from the beginning. But one asks if it is narrow for the Spirit to ONLY speak of Jesus Christ? What is there that is more important than Christ in this life and valley that we walk here below? Seriously answer that question! The Spirit testifies that we have been redeemed through the knowledge of sin and grace and He also continues to lead and guide us!
Abiding: "And I will abide with you even unto the end!" The child of God can live his life all the way unto death when he is about to take his last breath and the Spirit will comfort us all the way until the end when there is GLORY! What do we need in all of this life besides the Comforter who is the antidote to EVERYTHING even death!