Moshe Goldstein asks:
Where in the masechet does it mention that before going up to the azara, those who brought the korban would toivel their slaughtering knives?
Moshe Goldstein, Jerusalem
The Kollel replies:
I think you are referring to Pesachim 70a, where the Gemara states that if a knife is found in Yerushalayim on 14 Nisan one may use it for slaughtering immediately. Rashi (DH Shochet) explains that it does not need to be immersed because one may assume that if it had been Tamei the owners would have immersed it on 13 Nisan so that there would be Ha'arev Shemesh at the end of 13 Nisan and thus it would then be Tahor on 14 Nisan, ready to slaughter the Korban Pesach.
Kol Tuv,
Dovid Bloom