Musannaf Ibn Abi Shayba 28:367

Zayd ibn al-Hubab narrated to us, he said: al-Qasim ibn Ma'n narrated to us, from Ja'far, from his father, that 'Umar intended to assign stipends for the people, and his opinion was better than their opinion. They said: "Begin with yourself." He said: "No." So he began with those closest, then the next closest to the Messenger of Allah, may Allah bless him and grant him peace. He assigned a stipend for al-'Abbas, then 'Ali, until he had alternated between five tribes, until he reached the Banu 'Adi ibn Ka'b.