Reference for Pesachim 129:11

והלא דם התמצית מעורב בו רבי יהודה לטעמיה דאמר דם התמצית דם מעליא הוא דתניא דם התמצית באזהרה רבי יהודה אומר בהיכרת

I too, he answered them, spoke only of that which was received in a vessel. How does he know?<span class="x" onmousemove="('comment',' That it was caught in a vessel? For R. Judah prescribed this merely because the blood might have been spilled; then how can it be remedied with blood about which there is a doubt?');">¹²</span>

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