Zevachim 90: Which Takes Precedence, Holy and Consistent Offerings

The rabbis determine which offering should be made first in different pairings.  The pairings regard an item that is holy and an item that is offered constantly.  The rabbis have already established that more ordinary offerings and the holier offerings come before less frequent and the less holy offerings.  Thus a sin offering is brought before a burnt offering because the sin offering is met with atonement and its blood is sprinkled more completely (two in the place of four).

A number of proofs are suggested to establish these rules.  One example is the special offering offered on Shabbat even though a must offering is of greater holiness.  The proofs are rejected.  The Rambam has ruled that the priest can choose to bring the offering that he prefers - it is not necessary that holier or consistent offerings take precedence. 

It is interesting that the Rambam chooses to interpret this particular conflict with leniency.  So often we come across rulings that suggest one way or another.  To allow people to make choices is rare in our halacha.