Reference for Sanhedrin 59:2

סבר רבינא למימר היינו דריש לקיש א"ל רב נתן בר אמי הכי אמרינן משמיה דרבא כל כי האי גוונא חיישינן לב"ד טועין

but did not include [theusual phrase], 'We were in a session of three judges one of whom [subsequently]absented himself.'<span class="x" onmousemove="('comment',' Cf. Keth. 22a: If one of the three judges necessary for the authentication of a document died before signing it, the document should be so worded. ');">²</span>

Jastrow