Khuddakavatthukkhandhaka

Vinayapiṭaka · Cūḷavagga (2) · Vol. 7 · Section 175

[175] Now at that time, as a certain bhikkhu was chewing a tooth-wood (dantakaṭṭha) that was too short, it stuck in his throat. They reported this matter to the Blessed One. … "Bhikkhus, a tooth-wood that is too short should not be chewed; whoever should chew one commits an offense of wrong-doing (dukkaṭa). Bhikkhus, I allow a tooth-wood of four finger-breadths (caturaṅgula) as the minimum."

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.