1 Corinthians 15:9

Then he appeared to over five hundred brothers at once, most of whom remain until now, but some have also fallen asleep.

Then he appeared to James, then to all the apostles,

and last of all, as to the child born at the wrong time, he appeared to me also.

But by the grace of God I am what I am. His grace which was given to me was not futile, but I worked more than all of them; yet not I, but the grace of God which was with me.

Whether then it is I or they, so we preach, and so you believed.

Now if Christ is preached, that he has been raised from the dead, how do some among you say that there is no resurrection of the dead?