Reference for Bava Kamma 148:21

הא יש לו עדים חייב ושמעינן מינה מודה בקנס ואח"כ באו עדים חייב

BUT WOULD NOT HAVE TO MAKE FOUR-FOLD AND FIVE-FOLD PAYMENTS.<span class="x" onmousemove="('comment',' As the act of slaughter or sale was testified to by one witness who, in matters of fine, could be of no effect at all even for the purpose of imposing an oath. [V. J. Shebu. VI, and S. Strashun's Glosses, a.l.] so also is the admission of the thief himself of no avail in these matters. ');">¹⁸</span>

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