He told them things that are written in his epistles. And he used the OT scriptures to preach the Gospel 1 Cor 15:3-4
3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;
4 And that he was buried, and that he rose again the third day according to the scriptures:
Now explain how he used the OT scriptures to preach the Gospel of Christ. What all does the OT scriptures say about who Jesus is, what He has done, and for who and was He successful. Lets see you do that