The Mishna on our daf teaches that a korban Pesah that becomes invalid because it was taken out of Jerusalem or became tameh (ritually defiled) must be destroyed immediately on the 14th of Nisan. If, however, the sacrifice remained valid, but an outside problem will keep it from being eaten – e.g. all the people scheduled to eat it became tameh or died – the korban is left overnight and is only burned on the 16th of Nisan, after the first day of Yom Tov is over. Rabbi Yohanan ben Beroka disagrees and rules that even in the latter case the korban is destroyed immediately.
In an attempt to find the source for how to deal with kodashim (sanctified items) that have become unusable, the Gemara suggests an obvious story that bears great similarity to our case.
In (chapter 10) we learn about two of Aharon’s sons, Nadav and Avihu, who bring an esh zara – a strange fire – in the Mishkan and are killed by a heavenly fire. Aharon and his other children cannot eat the sin-offering and it is burned, a ruling that is questioned by Moshe, but defended by Aharon (see 10:16-20).
The Gemara decides that that case cannot be used as a proof-text for two reasons:
1. ma’ase she-haya – it is a story that happened that way.
And the sin-offering of Aaron that was burned on the eighth day of inauguration was mentioned only because the incident that took place, took place in this way. It was not mentioned in order to teach the of offerings.
Generally speaking, a passage from the Torah that deals with a point of law is carefully examined and analyzed. A story that appears in the Torah as narrative, however, is treated differently. Sometimes the Gemara simply concludes that we cannot learn from that story.
2. hora’at sha’a – it is an emergency measure.
This expression is used to describe several cases in which we find something described in the Torah that clearly deviates from what we know to be the accepted law. In such cases, an instruction may have been given to the Jewish People that directed the behavior at that particular time, but it is one that cannot be understood to impact on the halakha over the long-term. We find that the Sages also invoked this rule when a given situation demanded that a ruling be given that was more stringent – or more lenient – than usual. Under certain, limited, circumstances the Sages will even quote the passage et la’asot la-Shem heferu Toratekha (Tehillim 119:126) – that there are times that doing God’s will involves breaking the rules of the Torah.