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.”
1 John 2:27 “But the anointing which you have received from Him abides in you, and you do not need that anyone teach you; but as the anointing teaches you concerning all things, and is true, and not a lie, and just as it has taught you, you will abide in Him.”
Bring to remembrance:
Cause to remember, bring to mind, and through the gifts of the Spirit of words of knowledge and words of wisdom; the Spirit causes us to know that which we could not have otherwise known.
How was this of practical use? Remember who is present when Jesus speaks these words; all of the twelve apostles, except Judas Iscariot who betrayed Jesus, are present.
If they are to continue Jesus’ ministry, if they have any hope of fulfilling the Great Commission, they will need to know(remember)what He taught them. All they have is the Old Testament in which to study, and it doesn’t contain all that Jesus taught them. The Holy Spirit will cause them to remember what Jesus taught so that they can fulfill their ministry.
Now, here is another even more important reason for them to remember “all things” that Jesus said to them.
These men would write the New Testament!
Matthew, John, Peter, and James, were original Apostles who wrote Gospel accounts, as well as epistles. Then came Paul (known as the Great Apostle, who wrote about a third of the New Testament) his disciple Mark, and Doctor Luke, who wrote the Gospel according to Luke and the bulk of the Book of the Acts of the Apostles.
There may well have been other letters from some of the others that have not been found; at any rate, the New Testament would not be in existence without the Holy Spirit to “bring to remembrance all things which Jesus said to them.” Try to imagine any Christian ministry being able to exist without the wisdom, and teaching of Jesus as brought to the “remembrance” of the authors of the Bible.
This was/is the most important reason for the Holy Spirit’s reminders to those present, and later to Paul and Dr. Luke, that we might have such wisdom at our fingertips, revealed by the Holy Spirit.