Reference for Zevachim 231:19

והא כתיב (שמות יח, ב) ויקח יתרו [חותן משה] עולה וזבחים ההוא לאחר מתן תורה הוא דכתיב

- [He demanded] zebahim for food and burnt-offerings for sacrifice.<span class="x" onmousemove="('comment',' The answer renders zebahim animals for slaughtering, not sacrifices.');">²⁴</span> But surely it is written, And Jethro, Moses' father-in-law, took a burnt-offerin and sacrifices unto the Lord?<span class="x" onmousemove="('comment',' Ibid. XVIII, 12.');">²⁵</span>

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