daf bit: Avodah Zarah 23

[cellio]

We learn in the mishna: one should not place cattle in heathens' inns, because they are suspected of immoral practice with them. The g'mara responds: but according to a baraita we can buy their cattle for sacrifices, so shouldn't we be concerned there too? The g'mara then answers: the heathen surely won't sell an animal he has dedicated to idolatry, and for other immoral uses he won't put his profit at risk, so it's ok to buy their animals. After further discussion, there appears to be a dispute between R' Eliezer, who forbids buying a red heifer from heathens, and the sages, who permit it. The sages follow the baraita while R' Eliezer follows the mishna. Final answer? I don't know. (22b-23a.)

They're talking about the red heifer because, among animals offered in the temple, it's super-important.

Today's daf is 24.