From:
Theravāda Vinaya Theravāda Collection on Monastic Law
Mahāvibhaṅga The Great Analysis
Sekhiyakaṇḍa The chapter on training
Kabaḷavagga The subchapter on mouthfuls
49. Jivhānicchārakasikkhāpada 49. The training rule on sticking out the tongue
Tena samayena buddho bhagavā sāvatthiyaṁ viharati jetavane anāthapiṇḍikassa ārāme. At one time the Buddha was staying at Sāvatthī in the Jeta Grove, Anāthapiṇḍika’s Monastery.
Tena kho pana samayena chabbaggiyā bhikkhū jivhānicchārakaṁ bhuñjanti …pe…. At that time the monks from the group of six ate sticking out their tongues. …
“Na jivhānicchārakaṁ bhuñjissāmīti sikkhā karaṇīyā”ti. “‘I will not eat sticking out my tongue,’ this is how you should train.”
Na jivhānicchārakaṁ bhuñjitabbaṁ. One should not eat sticking out one’s tongue.
Yo anādariyaṁ paṭicca jivhānicchārakaṁ bhuñjati, āpatti dukkaṭassa. If a monk, out of disrespect, eats sticking out his tongue, he commits an offense of wrong conduct.
Anāpatti—There is no offense:
asañcicca …pe… if it is unintentional;
ādikammikassāti. if he is the first offender.
Navamasikkhāpadaṁ niṭṭhitaṁ. The ninth training rule is finished.