ויקרא, פרק ד׳, פסוק י״ח

Completing the atonement process for a sin offering involves a precise sequence of actions that connect the inner depths of the Tabernacle to the outside courtyard. Following an initial series of sprinklings, the priest applies blood to the horns of the inner incense altar, located deep within the Sanctuary itself [ביאור שטיינזלץ, ביאור יש״ר]. This careful application purifies the sacred space and signals the conclusion of the primary blood service. A practical rule applies during this phase: if the blood of the sacrifice was collected into several different cups, the priest is not forced to use the exact same cup he used for the first sprinklings. He is entirely permitted to take blood from a different cup, provided it belongs to the same offering [העמק דבר].

Once the inner service is complete, the priest takes all the remaining blood left in the vessel [ביאור שטיינזלץ] and carries it outside. This leftover blood is firmly excluded from being poured at the inner golden altar, despite the earlier service performed on its corners [גור אריה, דברי דוד, פרדס יוסף]. Instead, it must be poured at the base of the outer altar used for burnt offerings. This pouring must happen specifically on the lower foundation itself, rather than anywhere higher up on the altar's wall [פרדס יוסף].

The exact location for pouring this blood is the western base of the outer altar, which directly faces the entrance to the Tent of Meeting. The primary approach among commentators is that the location is not a general area, but a highly specific point aligned with the doorway [רש״י, מזרחי, גור אריה, דברי דוד]. There are different perspectives on why this specific western side is required. One approach roots this in the practical rule that one should not pass over an opportunity to perform a commandment. Since the priest exits the Sanctuary and walks toward the outer altar, the western base is the very first part he reaches, obligating him to pour the blood right there without walking further [מזרחי, משכיל לדוד].

Conversely, another view argues that pouring at the western base is an independent decree from God, rather than a mere result of the priest's walking path [שפתי חכמים]. A third perspective removes the rule of not passing over a commandment from the equation entirely. According to this view, the fact that the priest encounters the western base first is not a legal reason for the action, but simply a physical description of the Tabernacle's layout, reflecting the reality of the space closest to the entrance [דברי דוד].