Reference for Zevachim 216:21

א"ל רבי ירמיה תניא קרן וכבש וריבוע ויסוד מעכבין בבמה גדולה ואין מעכבין בבמה קטנה:

['He is liable'!] Surely he should say, [he] is excluded?<span class="x" onmousemove="('comment',' 'But there is no altar at a bamah', obviously means when this is permitted. But one is not liable then for offering up without, and so he should have said, this excludes (from liability) one who offers up on a rock or on a stone.');">²⁵</span> - This is what he means: Therefore if one offers up on a rock or on a stone when bamoth are forbidden, he is liable. R'Jose son of R'Hanina asked: As to the horn, the ascent, the base and squareness, are these indispensable at the bamoth?<span class="x" onmousemove="('comment',' These were indispensable to the altar in the Tabernacle: v. supra 62a.');">²⁶</span> - Said R'Jeremiah to him. It was taught: The horn, the ascent, the base and squareness were indispensable at the great bamoth,<span class="x" onmousemove="('comment',' Sc. at Nob and Gibeon; these were public bamoth.');">²⁷</span> but were not indispensable at minor bamoth.<span class="x" onmousemove="('comment',' Sc. private bamoth, which individuals built for themselves.');">²⁸</span> MISHNAH

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