Vinaykathā

Vinayapiṭaka · Cūḷavagga (2) · Vol. 7 · Section 310

[310] Now at that time bhikkhus, being scrupulous about carrying [furnishings] to the uposatha hall (uposathagga) or to the place of assembly, sat on the bare ground. Both their limbs and their robes became soiled with dust. They reported this matter to the Blessed One. "Bhikkhus, I allow [them] to be taken on a temporary basis (tāvakālika)."

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 7 · Section 321 — Vinaykathā