The answer is: Jonah

Matt 12:38-39 - Referring to the three days and nights that Jonah has spent in the belly of the great fish

In the Gospel of Matthew, when the Scribes and Pharisees demanded a sign, Jesus’ reference to Jonah wasn’t just a casual mention. It was richly packed with symbolism. Jonah, known for his reluctant mission to the city of Nineveh, is a poignant figure, highlighting themes of repentance, mercy, and resurrection. Jesus drew a parallel between Jonah’s three-day ordeal inside the fish and his own impending three days in the tomb—a speech bubble blew up revealing the miraculous reality of his resurrection.

Interestingly, Jonah's story is one of second chances. After initially fleeing from God's instruction, he eventually embraced his prophecy, resulting in a significant turnaround for the Ninevites. This mirrors the overarching message of change and hope offered through Jesus' ministry. The call to repentance isn't just for the "wicked" - the Ninevites recognized their failings and turned their lives around upon hearing God’s warning.

Also, this incident encourages us to reflect on the nature of signs. Jesus emphasizes that true signs aren't about theatrics but deeper truths, often involving humility and faith before something miraculous can occur. Just like Jonah’s story echoes through religious history, a repentant heart can bring about transformation—both personally and communally.

Whether viewed historically, morally, or spiritually, Jonah’s narrative serves as a reminder that signs abound when we approach each day with open hearts and minds, ready to create these moments of divine intervention in our lives.