As we have learned, having the wrong intention when bringing the korban can invalidate the sacrifice. The final Mishnahin the third perek (=chapter) of Masechet Zevahim teaches that this applies only to thoughts that focus on issues of time and place – and, in the cases of the Passover sacrifice and a sin-offering, having the wrong intent with regard to the purpose of the korban – but other inappropriate thoughts will not invalidate the sacrifice. Thus, intending to sprinkle blood in the wrong place on the altar, or thinking that the sacrifice would be brought or eaten by people who were temei’im – ritually defiled – or by areilim – people who were not circumcised – both of which are forbidden, will not affect the sacrifice. Similarly, in the case of the korban Pesach, which has unique requirements, like eating it roasted (see Shemot12:9) and not breaking any of the animals bones (see 12:46), if the person planned to eat it raw or to break its bones, the sacrifice itself would remain valid even though these things are forbidden.
The Gemara offers different explanations for these rules.
One suggestion is that even if these things actually took place – even if the sacrifices were eaten by temei’im and areilim, or even if the korban Pesach was eaten raw or had its bones broken – nevertheless the sacrifices would remain valid. Therefore such wrong intentions cannot be any worse that if these were actually done, and the sacrifice must remain valid.
Another approach suggested by the Gemara is that these activities are not controlled by the owner of the sacrifice. Rashiexplains that the person bringing the sacrifice cannot determine that temei’im and areilim will eat the sacrifice, since only the temei’im and areilim themselves can choose to do that. Some explain that even if the person bringing the sacrifice was personally tameh, still it is not in his hands since the kohanim will not allow him to touch the sacrifice while in a state of ritual defilement.