Khuddakavatthukkhandhaka

Vinayapiṭaka · Cūḷavagga (2) · Vol. 7 · Section 47

[47] Now at that time bhikkhus placed a bowl on a bench (pīṭha). Sitting down with a lapse of mindfulness, they sat upon it and broke the bowl. They reported this matter to the Blessed One. … "Bhikkhus, a bowl should not be placed on a bench. Whoever should place one there commits an offense of wrong-doing (dukkaṭa)."

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 7 · Section 597