How are the fifty oaths of Qasamah divided when multiple individuals are accused?
Chapter on Qasamah (Oaths regarding murder)
Al-Mughni
Book of Blood-Money (Diyyāt)
Primary text
If the claim is directed against a group, each individual is obligated to swear fifty oaths if the claim is based on intentional homicide. This position is supported by the Prophet's saying: "Your Jews will absolve you with fifty oaths," and in another narration, "So they swear fifty oaths for you and are absolved from his blood." This is because they are one of the two contending parties in Qasamah, and the oaths are reduced by their number, similar to the claimants.
Supporting text
Some of our companions suggest that the oaths should be divided among the accused proportionally, similar to the division among the claimants, but in this case, they are divided equally because the accused parties are equal in this matter, similar to the shares of the deceased's heirs. Al-Shafi'i holds two opinions regarding this matter, corresponding to two established juristic lines of reasoning.