The answer is: Psalms

Matthew 21:42 / Psalms 118:22

In Matthew 21:42, Jesus is weaving an intricate narrative with a rich tapestry of connections, specifically referencing Psalm 118:22. This verse becomes pivotal not just for its meaning but also for its placement in a moment where Jesus addresses rejection and eventual vindication. The imagery of the "stone which the builders rejected" serves as a double-edged metaphor. On one hand, it signifies how the very religious leaders of the day dismissed Jesus' mission and identity. On the other hand, it suggests that divine value can emerge even from what is overlooked or deemed insignificant by human standards.

What's fascinating is that Psalm 118 is part of a larger group of psalms known as the "Hallel," sung during major Jewish festivals, especially Passover. This connection amplifies the significance of Jesus' claim, pointing towards an anticipated Redemption that the Jews were looking for—albeit in a form they didn’t recognize.

In architectural terms, the "headstone of the corner" is crucial for the alignment and stability of a structure. Similarly, faith and belief serve as the cornerstones of life, providing direction and support in the tumultuous world of uncertainties. The parable isn’t just about Jesus’ own identity; it's about recognizing and embracing what truly holds our lives together—something surprisingly beautiful and vital, which one might initially overlook. So when confronting challenges, consider what “stones” in your life might transform into something extraordinary!