In Jainism, the concept of the “8 days” commonly refers to the Ashtanhika Parva, a special eight-day observance celebrated thrice a year by Shwetambar Jains, and also observed in some form by Digambar Jains.

The mention of these eight days (Ashtanhika) is found in the Jain Agamas. Specifically, it is described in the Kalpa Sutra and the Nishitha Sutra. These scriptures outline the significance of the eight days and the associated rituals and observances.

For example, the Nishitha Sutra (one of the Mool Sutras) references the Ashtanhika festival and prescribes the rules for penance and fasting during these auspicious days.

So, the Jain Agams that mention the eight days (Ashtanhika) include:

• Nishitha Sutra
• Kalpa Sutra
• Vyavahara Sutra (in the context of rituals and observances)

These Agams provide guidance on the importance and observance of these eight days within Jain practice.