No Gospel message was ever preached in the early church without including the resurrection as its validation. From Peter at Pentecost (Acts 2:32) to Paul before Agrippa (Acts 26:1-24), the resurrection was central to the gospel. It was also this central component of the gospel that spawned ridicule by people like those in Acts 17:32, “And when they heard of the resurrection of the dead, some mocked: and others said, We will hear thee again of this matter.”
Finally, Paul gave us the gospel in a nutshell, and it too included the resurrection.
1 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; 2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. 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: (1 Corinthians 15:1-4)