ויקרא, פרק ד׳, פסוק ל׳

The process of bringing a sin offering requires careful precision, particularly in how the animal's blood is handled. After the priest applies the required drops to the horns of the altar, he must properly dispose of whatever blood remains. The basic instruction is that the priest must pour the leftover blood from the collection vessel directly at the base of the altar [ביאור שטיינזלץ].

However, the exact phrasing of this command hints at a more complex scenario involving multiple collection cups. When dealing with a regular sin offering, the instruction emphasizes that the entirety of the remaining blood must be poured out. This contrasts with the rules for a leader's sin offering, where the command is phrased more narrowly. The primary approach among commentators is that this emphasis addresses a situation where the priest collected the blood into four separate cups and applied one drop to the altar from each individual cup. Because a portion was used from every vessel, the leftover blood in all four cups is considered valid remainders and must be poured at the base of the altar. In contrast, the narrower phrasing used for the leader's offering teaches that if the priest applied all the required drops from a single cup, the blood sitting in the unused cups is disqualified and is not poured at the altar's base.

A differing perspective [מלבי״ם, רד״צ הופמן] argues that even if the priest only used one cup to apply the blood, the contents of the untouched cups still count as valid remainders and must be poured at the base. According to this view, the narrower phrasing regarding the leader's offering has nothing to do with multiple cups. Instead, it serves to exclude the blood left behind inside the animal's neck, teaching that this specific blood is not poured at the altar's base.