The Black Sacrament is a ritual performed by those who wish to contact the Dark Brotherhood. The ritual consists of an effigy of the intended victim, formed from actual body parts including a skeleton, flesh and a heart. The person performing the ritual must then stab the effigy repeatedly with a dagger rubbed with the petals of the Nightshade plant while intoning "Sweet Mother, sweet Mother, send your child unto me, for the sins of the unworthy must be baptized in blood and fear."
In the absence of the Night Mother, Astrid and the Dark Brotherhood simply kept their eyes and ears open for any news of people attempting the Black Sacrament. Until a proper Listener could arise in the membership and be annointed by the Night Mother, the Brotherhood would be forced to use more conventional ways to obtain information on contracts. This method typically offered inferior coverage and the Brotherhood had to struggle to maintain its reputation.
Sweet Mother, Sweet Mother, send your child unto me, for the sins of the unworthy must be baptized in blood and fear.