I don't understand the gemara's question that 3 days is enough when we see that tanaaim hold we require either 30 days or 2 weeks. After all bikur mumim is only 4 days. where do we see that for mumim we need 2 weeks or 30 days?
allen schuldenfrei, baltimore, md
The Gemara's question is that we find regarding Pesach that there are either thirty days or two weeks given to learn the laws of Korbanos. Since people are involved in learning about the sacrifice, they will also pick out a good Korban if they see one.
Similarly, we should suspect that the idolater will be dealing with his sacrifice starting from thirty days or two weeks beforehand while he is involved in getting ready for his sacrifice. Any animal he sees during this time may be used for Avodah Zarah. (Based on the explanation of Avodah Berurah, in turn based on Tosfos).
All the best,
Yaakov Montrose