Ibn Mu'iz Sa'di said: I took my horse out to get fodder, and as I passed by one of the mosques of Banu Hanifa, I heard people there testifying that Musaylimah is the Messenger of Allah. I returned to Sayyiduna Abdullah ibn Mas'ud (may Allah be pleased with him) and informed him of this. So, Sayyiduna Ibn Mas'ud (may Allah be pleased with him) sent the police to those people, and they caught them and brought them. The people repented and retracted their statement, so Sayyiduna Ibn Mas'ud (may Allah be pleased with him) let them go (i.e., released them). Among them was a man called Abdullah ibn Nawahah; Sayyiduna Ibn Mas'ud (may Allah be pleased with him) killed him. The people said to him: You let everyone else go and killed this one? Sayyiduna Ibn Mas'ud (may Allah be pleased with him) replied: I was sitting with the Messenger of Allah (peace and blessings be upon him) when this man and another came as a delegation from Musaylimah. The Messenger of Allah (peace and blessings be upon him) said to them: "Do you both testify that I am the Messenger of Allah?" They both said: Do you testify that Musaylimah is the Messenger of Allah? The Prophet (peace and blessings be upon him) said: "I believe in Allah and His Messengers. If I were to kill envoys (delegates), I would have killed you both." Sayyiduna Ibn Mas'ud (may Allah be pleased with him) said: That is why I killed this man and ordered the demolition of their mosque, which was then demolished.
Hadith Referenceسنن دارمي / من كتاب السير / 2539
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده حسن ولكن الحديث صحيح، [مكتبه الشامله نمبر: 2545]
Hadith Takhrijاس روایت کی سند حسن اور دوسری سند سے حدیث صحیح ہے۔ دیکھئے: [أبوداؤد 2761] ، [أبويعلی 5097] ، [ابن حبان 4878] ، [الموارد 1629]
Brief Explanation
(Commentary on Hadith 2538)
Near Riyadh in Saudi Arabia, there is a place called Yamamah, where the people of Banu Hanifah resided. Among them was a liar named Musaylimah, who claimed prophethood and led the people of Yamamah astray. Many people fell into his trap. A delegation from him came to the Messenger of Allah (sallallahu alayhi wa sallam), which is referenced in the aforementioned hadith.
During the era of Sayyiduna Abu Bakr (radi Allahu anhu), an expedition was launched against this man and the Banu Hanifah under the leadership of Sayyiduna Khalid ibn al-Walid (radi Allahu anhu). Wahshi ibn Harb (the killer of Sayyiduna Hamzah radi Allahu anhu) with great difficulty killed this liar and deceiver, thus ending this tribulation.
The aforementioned hadith clarifies that it is not permissible to kill messengers who deliver messages, which is why the Messenger of Allah (sallallahu alayhi wa sallam) did not kill Abdullah ibn Nawahah and his companion despite their rudeness and indecency. Sayyiduna Ibn Mas‘ud (radi Allahu anhu) killed him because at that time he was not a messenger but a prisoner, and he was a denier of the Messenger of Allah (sallallahu alayhi wa sallam) and a follower of Musaylimah the liar.