Matthew 27:52 - 53
AMP - 52 The tombs were opened and many bodies of the saints who had fallen asleep in death were raised [to life]. 53 And coming out of the tombs after His resurrection, they went into the holy city and appeared to many people.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
My issue here is that an event such as this of graves being opened and dead people being in Jerusalem alongside an earthquake would be something which would have been reported elsewhere. I'm unaware of other accounts of this event.