Let’s read the words of the Lord in John 16:23-25, “And in that day ye shall ask me nothing. Verily, verily, I say unto you, Whatsoever ye shall ask the Father in my name, he will give it you. Hitherto have ye asked nothing in my name: ask, and ye shall receive, that your joy may be full. These things have I spoken unto you in proverbs: but the time cometh, when I shall no more speak unto you in proverbs, but I shall shew you plainly of the Father.” 

The Lord begins this portion by speaking of ‘that day’.  In that day, there would be no need to ask the Lord questions.  Up until that time, the Lord had been with His disciples in bodily form.  They often appealed to Him for guidance and asked many questions of Him.  This was proper and was their privilege to have the Lord Jesus among them where they could consult Him about all things.  What is He speaking of in referring to ‘that day’ when all this would change?

We need to back up to John 16:13-14 to find that answer.  In these verses, the Lord says, “Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come. He shall glorify me: for he shall receive of mine, and shall shew it unto you.”  ‘That day’ is the day when the Holy Spirit would come down to occupy and guide all believers.  ‘That day’ was the day of Pentecost when the Holy Spirit descended from the Glory and indwelt all believers.  I encourage you to read Acts, chapter 2, but we shall consider just a few verses here.  We read in Acts 2:1-4, “And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And THEY WERE ALL FILLED WITH THE HOLY GHOST, and began to speak with other tongues, as the Spirit gave them utterance.”

The Lord Jesus ascended back to Heaven after His death, burial, and resurrection.  He is no longer with us physically, but He sent the Holy Spirit down to indwell us and teach us.  We cannot physically approach the Lord Jesus and ask Him our questions, but by the leading of the Spirit, we can pray to the Father.  As we read in verse John 23, “And in that day ye shall ask me nothing. Verily, verily, I say unto you, WHATSOEVER YE SHALL ASK THE FATHER IN MY NAME, he will give it you.”

The Lord often spoke in parables to His disciples. (Read Matthew 13:10-13).  Now, with the advent of the Spirit, the Lord declares that He can now speak plainly of the Father, for the Spirit will give believers understanding. 

Now let’s look particularly at your question regarding John 16:26-27, “At that day ye shall ask in my name: and I say not unto you, that I will pray the Father for you: For the Father himself loveth you, because ye have loved me, and have believed that I came out from God.”  As we have seen, ‘that day’ is the day of the Holy Spirit’s descent to the earth to indwell all believers.  In the day in which we live, the Lord Jesus does not have to intercede on our behalf to convince the Father to answer our prayers.  We are assured of the Father’s love for us.  Because of that boundless love, the Father will respond to our requests and will answer our prayers according to His perfect will.  (1 John 5:14).  Why is the Father so much in love with us?  Because we are His and He is our Father because of our love for and faith in the Lord Jesus Christ.  Our Father loves to minister to our needs.  As the Spirit leads us to pray properly to the Father, He will answer and meet all our needs. 

It does need to be said that although the Lord Jesus does not need to convince the Father to answer our prayers, He is our one and only mediator as we read in 1 Timothy 2:5, “For there is one God, and one mediator between God and men, the man Christ Jesus.”  He constantly intercedes on behalf of His people before God’s throne.  (CC)  (532.4)