Amir al-Sha'bi narrates: When the Prophet (peace and blessings be upon him) passed away, some people became apostates. Some people said: "We will pray, but we will not pay zakah." The people said to Sayyiduna Abu Bakr (may Allah be pleased with him): "Will you accept this from them?" Sayyiduna Abu Bakr (may Allah be pleased with him) said: "If they refuse to give me even a young goat, I will fight them over it." Then he sent Sayyiduna Khalid bin al-Walid (may Allah be pleased with him). Adi bin Hatim came to al-Yamamah with a thousand men of the tribe of Tayyi'. The narrator says: Banu Amir had killed the officials appointed by the Prophet (peace and blessings be upon him) and burned them with fire, so Sayyiduna Abu Bakr (may Allah be pleased with him) wrote to Sayyiduna Khalid bin al-Walid (may Allah be pleased with him): "Kill Banu Amir and burn them with fire." He did so, until the women cried out. Then he went on until he reached the water, and they came out to him and said: "Allahu akbar, Allahu akbar (Allah is the Greatest, Allah is the Greatest); we bear witness that there is no god but Allah, and we bear witness that Muhammad (peace and blessings be upon him) is the Messenger of Allah." When he heard this, he held back from them. Sayyiduna Abu Bakr (may Allah be pleased with him) ordered him to march on until he reached al-Hirah, and then proceed to Syria. When he reached al-Hirah, he wrote to the people of Persia, and then said: "I would like not to leave until I have struck terror into them." So he raided until he reached Sura, where he killed and took captives; then he raided Ayn al-Tamr, killed and took captives; then he went on to Syria. Amir al-Sha'bi says: Ibn Buqaylah brought out the letter of Sayyiduna Khalid (may Allah be pleased with him) and showed it to me. In it was written: "In the name of Allah, the Most Gracious, the Most Merciful. From Khalid bin al-Walid to the marzubans (commanders) of Persia. Peace be upon whoever follows guidance. I praise Allah, besides whom there is no god, with a praise (for His act) that broke your unity, scattered your assembly, weakened your might and stripped away your kingdom. When this letter of mine reaches you, accept protection (dhimmah) from me, pay me the jizyah, and send me hostages. Otherwise, by Allah besides whom there is no god, I will meet you with a people who love death as you love life. Peace be upon whoever follows guidance."
Abu Ya'la recorded it. Its chain contains a narrator, Mujalid, who is da'if (weak), though he has been declared thiqah (trustworthy).