Musannaf Ibn Abi Shayba 28:345

Waki’ narrated to us, he said: Sufyan narrated to us, from al-Aswad ibn Qays, from a sheikh of theirs, he said: I heard ‘Umar ibn al-Khattab saying: "If I remain until next year, I will certainly attach the lowest of the Muhajirun to two thousand [dirhams], two thousand."