Imam al-Shafi'i (may Allah have mercy on him) said: "These are people who disbelieved after accepting Islam, such as Tulayhah, Musaylimah, (al-Aswad) al-Ansi and their companions."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / Q16726
Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) said: "While I was asleep, the treasures of the earth were brought to me, and two gold bracelets were placed on my hands. They became heavy upon me, and it was revealed to me that I should blow on them. I blew on them and they went away. I interpreted this to mean that in my own time there would be those two liars: one the man of San'a' and the other the man of Yamamah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16726
Muhammad bin Ishaq bin Yasar (may Allah have mercy on him) says: The first apostasy among the Arabs was that of Musaylimah in Yamamah, who was of Banu Hanifah, and of al-Aswad bin Ka'b al-Ansi in Yemen, during the very lifetime of the Prophet (peace and blessings be upon him); and Tulayhah bin Khuwaylid al-Asadi of Banu Asad, who claimed prophethood and used to compose rhymed speech for them all.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16727
Imam al-Zuhri (may Allah have mercy on him) says: When Allah made Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) caliph, and those of the Arabs who apostatised from Islam did so, Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) set out on campaign against them. When he reached Naq' in the direction of al-Baqi', he feared for Madinah, so he returned. He appointed Sayyiduna Khalid bin al-Walid (may Allah be pleased with him), the Sword of Allah, as commander, called on the people to go out with him, and ordered him to march through the outlying lands of Mudar and fight those of them who had apostatised from Islam, and then to march to Yamamah and fight Musaylimah the Liar. So Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) marched and fought Tulayhah al-Asadi the Liar, and Allah defeated him. Uyaynah bin Hisn bin Hudhayfah al-Fazari had followed him. When Tulayhah saw how many of his companions were being routed, he said: "Woe to you! What is defeating you?" A man among them said: "I will tell you what is defeating us: there is not a man among us except that he would love for his companion to die before him, while we are facing a people every one of whom loves to die before his companion." Tulayhah was fierce in battle, and on that day he killed Sayyiduna Ukkashah bin Mihsan and Sayyiduna Ibn Aqram (may Allah be pleased with them both). When the truth overcame Tulayhah, he dismounted, then accepted Islam and entered ihram for Umrah. He rode along among the people in safety until he passed by Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) in Madinah, then went on to Makkah and performed his Umrah. Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) proceeded towards Yamamah until he drew near a settlement of Banu Tamim, among whom was Malik bin Nuwayrah. He had collected the charity (sadaqah) of his people, but when the Prophet (peace and blessings be upon him) passed away he withheld it, so Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) sent a detachment (sariyyah) against him. (The narrator) then mentioned the hadith about the killing of Malik bin Nuwayrah. He said: Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) proceeded towards Yamamah until he fought Musaylimah the Liar and those of Banu Hanifah who were with him. Allah granted martyrdom to many of Khalid's companions from the Muhajirun and the Ansar, and Allah defeated Musaylimah and those with him. Musaylimah was killed that day by a freed slave of one of the Quraysh, named Sayyiduna Wahshi (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16728
Nu'man bin Buzruj says: Aswad the Liar came out; he was a man of Banu Ans. With him were 2 devils, one named Sahiq and the other Shaqiq, and they used to inform him of everything that happened in people's affairs. Aswad marched until he took Dhamar. Then he related the full story: how he married al-Marzubanah, the wife of Badhan, and how she gave him undiluted wine to drink until he was intoxicated. He entered Badhan's bed, which was made of feathers, and the bedding turned over on him. Fayruz and Khurrazadh bin Buzruj came in, and the woman indicated to them that he was in the bed. Fayruz seized him by his head and beard and wrung his neck until he broke it, and Ibn Buzruj stabbed him with a dagger and split him open from his collarbone to his pubic region, then cut off his head. They left, taking the woman with them along with whatever household goods they liked. Then he related another story, in which Fayruz came to the Commander of the Believers, Sayyiduna Umar bin al-Khattab (may Allah be pleased with him), who asked: Fayruz, how did you kill that liar? He replied: O Commander of the Believers, Allah killed him. He said: Yes, but tell me the story. So Fayruz related the whole story to him, and then went back to Yemen.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16729