Where did sangha day originate?

Sangha Day, also known as Magha Puja or Fourfold Assembly Day, originates from the Buddhist tradition and commemorates an event in the life of the Buddha. It marks the day when the Buddha delivered a significant sermon to 1,250 enlightened monks who spontaneously gathered to hear him speak. This event underscores the importance of the Sangha, or community of monks, in Buddhism. Celebrated on the full moon day of the third lunar month, it emphasizes the values of community, harmony, and spiritual practice.