Qasāmah, and the enforcement of retribution through it, is a legitimate right—the caliphs themselves have carried out retaliation on its basis. He therefore said, “What do you say, Abū Qilābah?” and set me before the people.
I replied, “Commander of the Believers, you have before you the nobles of the Arabs and the commanders of the troops. Suppose fifty men were to testify that a certain man committed adultery in Damascus, even though they had not seen him—would you stone him?”
He said, “No.”
I continued, “And if fifty men testified in your presence that a man had stolen in Ḥimṣ, yet they had not seen him—would you cut off his hand?”
He said, “No.”
In one version I added, “Then why is it that if they testify he killed someone in such-and-such a land while they are here with you, you would exact retaliation on their testimony?”
So ʿUmar ibn ʿAbd al-ʿAzīz wrote concerning qasāmah: “If they present two upright witnesses that so-and-so killed him, then exact retaliation; but no one is to be killed on the strength of the testimony of the fifty who swore the oaths.”

They further argue that one of the fundamental principles is that oaths have no effect when it comes to shedding blood, and that another principle states, “The burden of proof is on the claimant, and the oath is upon the one who denies.” Among their proofs is that they do not find, in any of the relevant ḥadīths, the Messenger of Allah—may Allah bless him and grant him peace—actually ruling by qasāmah; rather, it was a pre-Islamic practice, and the Prophet merely accommodated them to show that such a judgment is not binding under Islamic fundamentals. Hence he said to them, “Will you swear fifty oaths”—meaning the custodians of the blood, the Anṣār. They replied, “How can we swear when we did not witness the crime?” He said, “Then the Jews will swear for you.” They answered, “How can we accept the oaths of a people who are disbelievers?” They say: had it been the Sunnah for the heirs to swear even without witnessing the act, the Messenger of Allah—may Allah bless him and grant him peace—would have said to them, “That is the Sunnah.”

Since these reports do not constitute an explicit text obligating judgment by qasāmah and are open to interpretation, it is preferable, they maintain, to interpret them in line with foundational principles. Those who uphold qasāmah—foremost among them Mālik—consider the Sunnah of qasāmah an independent Sunnah that specifies (creates an exception to) the general principles, just like other specifying Sunnahs. He held that its rationale is the safeguarding of blood: killings had become frequent while witnesses were scarce, for the murderer seeks out secluded places. Therefore this Sunnah was instituted to protect lives. Yet, he is challenged with the cases of highway robbery and theft, for witnesses are likewise scarce there. For that reason Mālik accepted the testimony of those who had been robbed against the robbers, even though this contradicts general principles, for the robbed parties are themselves the claimants. Allah knows best.

Second Issue
The scholars who accept qasāmah have differed over what liability it establishes. Mālik and Aḥmad held that it grants the right to retaliation in intentional homicide and the diyah in manslaughter. Al-Shāfiʿī, Sufyān al-Thawrī, and a group said it establishes only the diyah. Some Kūfan jurists maintained that it serves merely to dismiss the claim, for in principle the oath is required of the defendant. Others said that the defendant must swear and pay the diyah; on this view it serves only to bar retaliation. Thus four separate opinions emerge regarding the outcome for those who swear in qasāmah.

The principal evidence cited by Mālik and those who agree with him is the ḥadīth transmitted by Ibn Abī Laylā from Sahl ibn Abī Ḥathmah, in which