It is not mandatory to kill it until this act is proven against it by evidence. As for if the perpetrator confesses, if the animal belongs to him, it is established by his confession. But if it belongs to someone else, it is not permissible to kill it based on his statement, because it is a confession against another's property, and thus it is not accepted, just as if he confessed to it belonging to someone other than its owner. And is this established by two just witnesses and a confession four times (8), or is what is considered for adultery required in it? There are two views, which we shall mention in their proper place, if Allah the Exalted wills.
1558 - Issue; He said: (And the one upon whom the hadd punishment is mandatory, from those I have mentioned, is the one who confesses to adultery four times.)
The summary of this is that the hadd is not mandatory except through one of two things: a confession or evidence. If it is established by a confession, a confession of four times is required. This is the opinion of al-Hakam, Ibn Abi Layla, and the People of Opinion (Ashab al-Ra'y). Al-Hasan, Hammad, Malik, al-Shafi'i, Abu Thawr, and Ibn al-Mundhir said: He is punished by a single confession, due to the statement of the Prophet (may Allah bless him and grant him peace): "Go, O Unays, to the wife of this man, and if she confesses, then stone her" (1). A single confession is a confession, and he made stoning mandatory upon her by it. He also stoned the Juhaniyya woman, even though she only confessed once (2). Umar said: Stoning is a mandatory right upon whoever commits adultery and has been previously married (ihsan), if evidence is provided, or if there is pregnancy, or confession (3). And because it is a right, it is established by a single confession, like all other rights. As for us, we rely on what Abu Hurayra reported, saying: A man from the Aslam tribe came to the Messenger of Allah (may Allah bless him and grant him peace) while he was in the mosque and said: "O Messenger of Allah, I have committed adultery." He turned away from him, so he moved to the side facing him and said: "O Messenger of Allah, I have committed adultery." He turned away from him until he had done this four times. When he had testified against himself four times, the Messenger of Allah (may Allah bless him and grant him peace) called him and said: "Are you insane?" He said: "No." He said: "Have you been previously married?" He said: "Yes." Then the Messenger of Allah (may Allah bless him and grant him peace) said: "Stone him." It is agreed upon (4). If the hadd were mandatory upon a single confession, the Messenger of Allah (may Allah bless him and grant him peace) would not have turned away from him, because it is not permissible to abandon a hadd that has become mandatory for Allah the Exalted. Nu'aym ibn Hazzal also reported his hadith, which includes: "Until he said it four times, and the Messenger of Allah (may Allah bless him and grant him peace) said: 'You have said it four times, so with whom?'" He said: "With so-and-so." Reported by Abu Dawud (5). This is an explanation from him that indicates that the confession of four times is what makes it mandatory. Abu Barza al-Aslami reported that Abu Bakr al-Siddiq said to him in the presence of the Prophet (may Allah bless him and grant him peace): "If you confess four times, the Messenger of Allah (may Allah bless him and grant him peace) will stone you" (6). This is indicative from two aspects; one of which is that the Prophet (may Allah bless him and grant him peace) approved him for this and did not deny it, so it is in the position of his own statement, for he does not approve of an error. Second, he must have known this from the judgment of the Prophet (may Allah bless him and grant him peace), otherwise, he would not have dared to say it in his presence. As for their hadiths, "confession" is a verbal noun that applies to both small and large amounts, and our hadith clarifies it and shows that the confession by which it is established is four times.
(8) In the original: "once". (1) Its authentication was previously mentioned on page 313. (2) Its authentication was previously mentioned on page 311. (3) Its authentication was previously mentioned in: 11/11.