Zevachim 4 - For the Sake of the Sacrifice
There are four distinct actions in bringing a sacrifice, and each is considered a separate sacrificial service: slaughter, reception of the blood into a Temple vessel, carrying the blood to the Altar, and throwing it on the Altar. Each of the four services has to be done for the sake of the sacrifice - that is, the one who is doing the service needs to keep in mind, and not declare otherwise, that he is doing this service for the peace offering, burnt offering, etc.
How do we know it? The Torah said, "And if his slaughter is for the sake of peace offering." You could argue and say that the Torah needs to specify that it is a peace offering, and not something else. To that the answer is that the Torah already called it a peace offering in "one carries the blood of the peace offering." What does it teach then by saying "his slaughter is for the sake?" - that it needs to be for the sake of the specific offering.
The "for the sake" requirement for other services is derived from similar verses. There is also an analogous requirement "for the sake of the owner of the sacrifice."
Art: Gustave Bauernfeind - At the Entrance to the Temple Mount, Jerusalem