The Holy Ghost/Spirit refers to the written word:
Joh_16:13 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.
Joh 16:14 He shall glorify me: for he shall receive of mine, and shall shew it unto you.
Joh_14:26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.
Joh_15:26 But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me:
As an example, of the Holy Ghost/Spirit speaking, He referred to the OT:
1Ti_4:1 Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;
This is a reference to Daniel, etc.