Musnad Ahmad 325:1

Muhammad ibn Fudayl narrated to us, he said: Yahya ibn Sa’id narrated to us, from Bashir ibn Yasar, from men among the companions of the Prophet, may God bless him and grant him peace, whom he reached, who mentioned: "That when the Messenger of God, may God bless him and grant him peace, prevailed over Khaybar, and Khaybar became for the Messenger of God and the Muslims, they were unable to work it, so they handed it over to the Jews to manage it and spend upon it, on the condition that they have half of what comes out of it. The Messenger of God, may God bless him and grant him peace, divided it into thirty-six shares, each share comprising one hundred shares. He allocated half of all that to the Muslims, and within that half were the shares of the Muslims and the share of the Messenger of God, may God bless him and grant him peace, along with them. He allocated the other half for those who arrive to him from the delegations, the affairs, and the calamities of the people."