"These things I have spoken to you in figurative language; but the time is coming when I will no longer speak to you in figurative language, but I will tell you plainly about the Father. In that day you will ask in My name, and I do not say to you that I shall pray the Father for you; for the Father Himself loves you, because you have loved Me, and have believed that I came forth from God. I came forth from the Father and have come into the world. Again, I leave the world and go to the Father."
Some examples of Jesus' figurative language from that evening include John 15:1-8 and 16:16-24. Although these truths are not exceedingly difficult for us to understand today, the apostles were in the dark regarding much of what Jesus spoke on this occasion (because of their incorrect assumptions about the nature of Jesus' kingdom). After His resurrection, their spiritual understanding will increase dramatically (cf. Luke 24:45; John 14:26; 16:13).
It would not be necessary for Jesus to "pray the Father" for them because the Father Himself loved them (and in the strongest sense, since they believed and obeyed Jesus). Thus, Jesus is not saying in this context that He will not act as the Christian's High Priest, Mediator, and Intercessor. Other passages plainly teach about His activities in these roles (cf. Rom. 8:34; I Tim. 2:5; Heb. 4:14; 7:25). Jesus is saying that they can petition the Father themselves; it would not be necessary for Him to make requests to the Father on their behalf.
"I came forth from the Father and have come into the world. Again, I leave the world and go to the Father" - Although Jesus had taught all of these points previously, He had never declared these truths as plainly as He did here (i.e., His divine nature and association with the Father, His former abode in heaven, His entrance into this world, and His intention to leave the world and return to the Father; cf. John 1:1ff; 6:38; 14:2ff).
"His disciples said to Him, 'See, now You are speaking plainly, and using no figure of speech! Now we are sure that You know all things, and have no need that anyone should question You. By this we believe that You came forth from God'" (John 16:29,30). They now clearly understand that Jesus would return to heaven (since He had come from the Father). However, they did not understand how or when this return would take place.
"Now we are sure that You know all things" - The fact that Jesus read their minds in 16:19 impressed them (along with all of the other wonderful signs they had witnessed over their several years spent with Him). They have faith in Him as the Messiah, the one who "came forth from God."
"Jesus answered them, 'Do you now believe? Indeed the hour is coming, yes, has now come, that you will be scattered, each to his own, and will leave Me alone. And yet I am not alone, because the Father is with Me. These things I have spoken to you, that in Me you may have peace. In the world you will have tribulation; but be of good cheer, I have overcome the world'" (John 16:31-33).
"Do you now believe?" - Jesus does not doubt their faith but asks this question to point out the weakness of it. Jesus' hour had come, literally. It would be but a short time before the betrayer would come and Jesus would be arrested. The faith of the apostles would then be stretched to the breaking point. Although Jesus would definitely be hurt by the desertion of nearly all of His apostles, He would be comforted in knowing that the Father was with Him. May we find comfort in knowing that when we stand with God, He stands with us, even if the world is against us (cf. II Tim. 4:16-18)!
"These things I have spoken to you, that in Me you may have peace. In the world you will have tribulation; but be of good cheer, I have overcome the world" - It is remarkable that in this last hour, in these final words of Jesus to His apostles, and in the face of unparalleled agony, He speaks of peace that would be theirs. Inner peace and tranquility are available in Him to all disciples despite the trials, afflictions, and persecutions of this world. Such is the case because Jesus is victorious over sin and death (and all who follow Him faithfully will share in the victory and the accompanying joy). When one knows that he will be victorious ultimately, how can he not have inner peace?
Jesus states here that He had overcome the world (past tense). His mission was so near to being completed that He speaks of it as already being accomplished. The only thing that remained for Him to do was to submit to His enemies and be crucified for the sins of the world!