Transitioning from the deep impurity of death back to a state of purity requires precise physical actions and focused intent. The process relies on simple materials, beginning with hyssop, an ordinary, lowly plant. It is typically gathered in a bundle of three stalks and remains valid for use even if it becomes worn or some stalks fall off [רלב״ג, רש״ר הירש, אדרת אליהו]. The use of such an unassuming plant conveys a profound lesson: one who lowers himself and acts with humility will ultimately find purity [בכור שור]. This hyssop is dipped into a vessel of living water, which possesses the unique capacity to wash away the impurity of death [בכור שור]. The vessel must contain a sufficient amount of water for the sprinkling from the very start, and the hyssop must be actively dipped into the water rather than simply absorbing it [תורה תמימה, אדרת אליהו].
The act of sprinkling must be performed during the day by someone who is pure [רלב״ג, אדרת אליהו]. The primary approach among commentators is that this role is reserved for males, though it can even be performed by a minor, provided the child has enough maturity to understand the action, as the process requires deliberate intent [תורה תמימה, רש״ר הירש, אדרת אליהו, רלב״ג]. Alternatively, one perspective suggests that this pure individual should ideally be a priest [אבן עזרא]. The person performing the sprinkling does not contract impurity from the impure individual receiving it. While the sprinkler must act with focused intent, the efficiency of the process is remarkable: a single dip of the hyssop can yield multiple sprinklings, and a single sprinkle can purify numerous people and vessels simultaneously, provided a drop of water touches an exposed surface of each [רלב״ג, הכתב והקבלה, רש״ר הירש].
When impurity occurs within an enclosed space, the structure itself—whether made of leather, linen, wool, or goat hair—contracts impurity and transfers it to everything situated beneath it [רלב״ג, רש״ר הירש, ביאור שטיינזלץ]. However, objects resting above the structure remain unaffected [הדר זקנים]. To restore purity, each item within the space must be sprinkled individually; purifying the outer structure does not automatically purify its contents [תורה תמימה]. The sprinkling is also administered to the people present, a category that includes young children and newborns [תורה תמימה, רלב״ג, אדרת אליהו]. This applies only to those physically present in the room, specifically excluding a fetus in its mother's womb [אדרת אליהו]. Much like inanimate objects, the individuals receiving the sprinkled water do not need to be consciously aware of the procedure to achieve purity [רש״ר הירש, אדרת אליהו].
Beyond enclosed spaces, impurity can also be contracted through direct physical contact in an open field [ביאור יש״ר, העמק דבר]. The progression of these encounters moves from a small fragment of a body to a whole corpse, and finally to a grave [רלב״ג]. Distinguishing between these various scenarios requires the specific traditions of the Oral Torah, as they can appear quite similar at first glance [ברכת אשר על התורה]. For instance, touching a bone refers to a human bone at least the size of a barleycorn [העמק דבר, תורה תמימה]. Because such a bone lacks flesh and sinews, it transfers impurity only through direct touch or carrying, but not by merely sharing a roof [תורה תמימה]. A careful distinction is also made between a severed limb from a living person that lacks enough flesh to heal, and a similar limb taken from a corpse [תורה תמימה, אדרת אליהו, ברכת אשר על התורה]. Finally, contact with a grave includes ancient burial sites that predate the giving of the Torah, such as the grave of the first man, or the graves of non-Jews. Like a dry bone, these sites transfer impurity through direct touch but do not project impurity to objects or people sharing the same overhead cover [תורה תמימה, אדרת אליהו, ברכת אשר על התורה].