Luk 8:9-10 His disciples began questioning Him as to what this parable meant.
And He said, "To you it has been granted to know the mysteries of the kingdom of
God, but to the rest it is in parables, so that SEEING THEY MAY NOT SEE, AND
HEARING THEY MAY NOT UNDERSTAND. "
(however, later in Luke 18:34: But the disciples understood none of these
things, and the meaning of this statement was hidden from them, and they did not
comprehend the things that were said. ) But the verse that I was remembering was
Lk 24:45 - not the Holy Spirit, rather Jesus after the resurrection:
Luk 24:44-47 Now He said to them, "These are My words which I spoke to you while I
was still with you, that all things which are written about Me in the Law of
Moses and the Prophets and the Psalms must be fulfilled." Then He opened their minds to understand the Scriptures, and
He said to them, "Thus it is written, that the Christ would suffer and rise
again from the dead the third day, and that repentance for forgiveness
of sins would be proclaimed in His name to all the nations, beginning from
Jerusalem.
Also in John
Joh 14:25-26 "These things I have spoken to you while abiding with you. 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 that I
said to you.
Joh 16:13-14
"But when He, the Spirit of truth, comes, He will guide you into all the truth;
for He will not speak on His own initiative, but whatever He hears, He will
speak; and He will disclose to you what is to come. (14) "He will glorify Me,
for He will take of Mine and will disclose it to you.