The answer is: Day of Atonement

Lev 16

The Day of Atonement, known in Hebrew as Yom Kippur, is one of the most sacred days in the Jewish calendar and carries profound significance in the context of the Temple. It’s the only day when the High Priest could step into the Holy of Holies, the innermost sanctuary of the Temple housing the Ark of the Covenant, symbolizing God’s presence on Earth. Isn't it striking how such a pivotal moment in spiritual practice revolves around themes of atonement and cleansing?

Lev 16 provides a poignant glimpse into the rigorous rituals this day entailed. The High Priest would meticulously prepare, first performing sacrifices for his own sins before making atonement for the people’s. He would also release a scapegoat into the wilderness, symbolically carrying away the congregation's iniquities. This ritual reflects the remarkable evolution of religious customs from physical sacrifices towards more introspective, spiritual atonement in contemporary interpretations.

Interestingly, the number ten plays a symbolic role here: there are ten days in the lead-up to Yom Kippur, each counting down the opportunity for repentance. This aspect aligns with broader biblical themes, such as the ten plagues in Exodus and the Ten Commandments prescribed in the Torah. The threads of purification and renewal seamlessly connect the past and present spiritual practices that promote reflection on our actions and relationships. The legacy of these traditions continues to evoke thought on personal and communal accountability, a universal human experience that transcends time.