Sayyiduna Sahl bin Abi Hathmah (may Allah be pleased with him) said that the elders of his people informed him, and he mentioned the hadith of qasamah. In it is that the Messenger of Allah (peace and blessings be upon him) wrote to them about it, and they wrote back: "By Allah, we did not kill him."
(b) Sayyiduna Abdullah bin Ukaym (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) wrote to the land of Juhaynah.
(c) Sayyiduna Amr bin Hazm (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) wrote a letter to the people of Yemen, in which he wrote about the obligatory shares, the sunnahs and the blood-monies, and this letter was read out to the people of Yemen.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20410