זבחים 96:1 — Soncino English Talmud

Then why should the pots in the Temple be broken: let them be returned to the kiln? — Said R. Zera: Because kilns are not permitted in Jerusalem. Abaye retorted: And are then refuse heaps permitted in the Temple court? [Abaye, however,] had overlooked what Shemaiah of Kalnebo recited: The fragments of earthen vessels were swallowed up in their place. Now, when R. Nahman said in Rabbah b. Abbuha's name, ‘The Temple oven was of metal’,let it be an earthen one, since It was heated within? — Since the Two Loaves and the Shewbread were baked in the oven and were sanctified in the oven, it became a service vessel, and we do not make earthen service vessels. 8^ᵃ^ᵇ^ᶜ^ᵈ^ᵉ^ᶠ^ᵍ^ʰ

^ᵃnote:Which would expel what they had absorbed.
^ᵇnote:On account of the smoke.
^ᶜnote:Sc. of broken potsherds.
^ᵈnote:Kar-nebo, ‘the city of Nebo’, conjectured to be Borsippa, Funk, Monumenta, I, p. 299.
^ᵉnote:Yoma 21a.
^ᶠnote:And thus what it absorbed of the sacrifices would be expelled.
^ᵍnote:V. Lev. XXIII, 15-17; Ex. XXV, 30.
^ʰnote:Offerings such as meal-offerings, loaves etc. were sanctified by being placed in service vessels. The Two Loaves and the Shewbread, however, were not placed in a service vessel, but were kneaded and shaped outside the Temple court, then brought in and baked in the oven. Thus the oven itself sanctified them, and ipso facto ranked as a service vessel.