Is the Qasamah established if one heir is absent, or if one heir abstains from taking the required oaths?
Chapter on Qasamah (Oaths regarding murder)
Al-Mughni
Book of Blood-Money (Diyyāt)
Primary text
If one of the two heirs is absent and the present heir makes the claim without the absent one, or if both claim against one person but one of them refuses to swear the required oaths (nakul), the killing is not established according to the literal reading of Al-Khiraqi's position. This is because the oath substitutes for evidence, and nothing of the right can be established until the complete evidence is present, analogous to a joint debt claim where one party fails to provide full proof.
Supporting text
The view of Abu Bakr and Al-Qadi, along with the position of Al-Shafi'i, supports the establishment of the Qasamah in this scenario, as there is no explicit mutual denial. If one heir is absent, the present heir swears the fifty oaths and is entitled to half the blood money (diyah), similar to cases where one heir is a woman or a minor.