You’re hearing “3 thui” and “4 thui” for the Jain vows called Tivihār and Chauvihār. In everyday Gujarati/Prakrit speech, “thui” here means “vihār” (modes of intake).

Why two types

• Jain Āgamas classify four ways of intake after filtering etc.: eating (āsana/āhāra), drinking (pāna), chewing (khāima), and licking/sucking (sāima).
• “4 thui” (Chauvihār) = abstaining from all four after sunset until sunrise.
• “3 thui” (Tivihār) = abstaining from three of the four; typically only water is permitted, while eating, chewing, and licking are stopped.

Simple definitions

• Chauvihār (4 thui): no food, no water, no chewing, no licking till next sunrise.
• Tivihār (3 thui): no food, no chewing, no licking; only water may be taken till next sunrise. Some places also allow necessary medicine; others keep medicine only under exception.

Why this practice

• To live Ahimsā more strictly at night (when tiny beings are more active).
• To strengthen Saṃyam (self‑restraint) and reduce rāga-dveṣa linked to taste.

Traditions

• Both Digambar and Śvetāmbara follow these abstinences. Minor local usage can differ (e.g., whether medicine is grouped with water under Tivihār or kept as an exception), but the core idea remains the same: Chauvihār stops all four; Tivihār stops three.

For short references and Pachkhan wordings:

• Tivihār / vows explanation
• Tivihār Pachkhan (audio/notes)