Murder of the Pure Soul or Qatl al-Nafs al-Zakīyya (Arabic: قتل النفس الزكية) is the murder of a person called "al-Nafs al-Zakiyya" (the Pure Soul), which is, according to Shiite hadiths, a decisive sign of the Reappearance of Imam al-Mahdi (a). The event is going to happen after the Reappearance and fifteen days and nights before the Uprising of Imam al-Mahdi (a) in al-Masjid al-Haram. He is from the progeny of Imam al-Husayn (a).
"Al-Nafs al-Zakiyya" is the title of a person called Muhammad b. al-Hasan. He is called "al-Nafs al-Zakiyya" (the Pure Soul) in hadiths because of his asceticism and worships. He is from the progeny of Imam al-Husayn (a), and is thus a Husayni sayyid.
The event of the murder of the Pure Soul is said in hadiths to be decisive, which implies its significance. The event has been variously characterized in hadiths as "inevitable", "there is no way that it cannot happen" and "[the Imam] does not start the uprising until [this event]". The decisiveness is emphasized in Humran b. A'yan's hadith from Imam al-Sadiq (a) along with other decisive signs of the Reappearance of Imam al-Mahdi (a) (such as the Heavenly Cry, Sufyani's Riot, Yamani's Riot, Khasf al-Bayda').
As implied by hadiths, the task of the Pure Soul is to deliver messages to the Imam (a). After the Reappearance of Imam al-Mahdi (a) and the global announcement of the Reappearance by a Heavenly Cry, he tells his companions that people of Mecca do not want him although he is sent to guide them; thus, a person just like me should tell them so that they receive the ultimatum. He asks one of his companions to tell people of Mecca that he was sent by al-Mahdi (a) who wants to tell them:
When the messenger will start talking, people of Mecca will attack and decapitate him.
The murder of the Pure Soul is going to happen after the Reappearance and fifteen days before Imam al-Mahdi's uprising. Al-al-Shaykh al-Saduq cited a hadith with a chain of transmitters up to Imam al-Sadiq (a) according to which, there will only be fifteen nights between the uprising of the Qa'im of the Family of Muhammad and the murder of the Pure Soul.
Al-Nafs al-Zakiyya has a brother who is also going to be martyred in Mecca. 'Ammar b. Yasir is quoted as saying that when al-Nafs al-Zakiyya and his brother are murdered, an angel close to God will cry: "al-Mahdi is your emir and your guardian and he is the one who fills the Earth with righteousness and justice".
Supporters of Muhammad b. 'Abd Allah al-Mahḍ (d. 145/762) appealed to certain hadiths to identify him as al-Nafs al-Zakiyya.
He is different from al-Nafs al-Zakiyya who, according to other hadiths, is going to be martyred behind Kufa together with seventy helpers of his. Some contemporary authors have identified the latter with Muhammad Baqir al-Hakim and his helpers who were martyred in Najaf (which is behind Kufa).