The answer is: When the plague of death of the firstborn was brought upon the land of Egypt

Exodus 12:12-13 - The Passover festival was instituted as a pivotal moment for the Israelites during their deliverance from slavery in Egypt, marking the final plague. Interestingly, the themes of sacrifice and redemption resonate throughout Scripture, culminating in Christ’s sacrificial death during Passover, establishing a new covenant for believers (Luke 22:20).

The festival of Passover, a cornerstone of Israelite identity, began during a gripping moment of anguish and divine intervention in Egypt. The story unfolds in Exodus, where God instructed the Israelites to mark the doorposts of their homes with lamb's blood to shelter them from the final plague—the death of the firstborn. This act of obedience protected them, leading to their liberation. Isn't it fascinating how the graphic imagery of lamb's blood has echoed through centuries, resonating in various interpretations and religions?

The symbolism of the lamb extends beyond Exodus; Jewish tradition holds it dear, and it emerges in the Christian narrative as an archetype of sacrifice. Moreover, this concept reappears in the Revelation of John, where Jesus is referred to as “the Lamb,” signifying hope and redemption amidst turmoil—a universal theme across cultures.

Passover is not only about historical remembrance but also a time of communal empathy and contemplation; it encodes a message of freedom that transcends borders and traditions. Practiced to this day, Seder meals and the recitation of the Haggadah help new generations connect with their heritage. Celebrated not just as an annual event, Passover rejuvenates the spirit of resilience in adversity, calling everyone to appreciate moments of deliverance, symbolic or personal. This is a vibrant reminder that healing and liberation are perpetual human themes echoing throughout the Scriptures—marking transitions in individual lives and collective histories alike.