Zevachim 8: Offering Fit for Sacrifice

The Gemara discusses the sin offerings and whether or not it must be done for its own sake.  The rabbis then find proof texts to justify why a sin offering offered not for its own sake is not valid.  Offerings brought for one who is a nazirite, or for one who is ending their seclusion for having za'arat, a specific skin condition - are considered.  Many rabbis believe that we cannot compare these different categories of offerings.

We are are introduced to a baraita regarding a different offering brought for its own sake - or no.  It states that a korban Pesach, a paschal offering, that is slaughtered at the proper time - erev Pesach - is fully kosher as long as it was slaughtered for its own sake.  If not, it is not fit for sacrifice.