Musnad Ahmad 283:2

Sufyan informed us, from Yahya ibn Sa'id, who heard Bashir ibn Yasar, the freed slave of Banu Harithah, say—Sufyan said: This is the hadith of Ibn Harithah—informing about Sahl ibn Abi Hathmah: Abdullah ibn Sahl of the Ansar was found killed in a well among the wells of Khaybar. His two paternal uncles and his brother came to the Messenger of Allah, may Allah bless him and grant him peace. His brother was Abd al-Rahman ibn Sahl, and his two paternal uncles were Huwayyisah and Muhayyisah. Abd al-Rahman went to speak before the Messenger of Allah, may Allah bless him and grant him peace, so he said: "The elder, the elder." Then one of his two paternal uncles spoke—either Huwayyisah or Muhayyisah; Sufyan said: I forgot which of them was the elder—and they both said: "O Messenger of Allah, we found Abdullah killed in a well among the wells of Khaybar." Then they mentioned the Jews, their evil, and their enmity. He said: "Let fifty of you take an oath that the Jews killed him." They said: "How can we take an oath on what we did not see?" He said: "Then the Jews will absolve you by fifty [of them] swearing that they did not kill him." They said: "How can we be satisfied with their oaths when they are polytheists?" He said: So the Messenger of Allah, may Allah bless him and grant him peace, paid the blood money for him from his own [resources]. A young she-camel from it kicked me. It was said to Sufyan regarding the hadith: "And you are entitled to the blood of your companion?" He said: "That is it."