Musannaf Ibn Abi Shayba 37:607

Abu Usama narrated to us, he said: Abdullah bin al-Walid narrated to us, from Musa bin Abdullah bin Yazid, from Abu Dhabyan al-Azdi, who said: Umar said: "What is the matter with you, O Abu Dhabyan?" I said: "I am on two thousand and five hundred [dirhams/dinars]." He said: "Then acquire sheep, for it is imminent that young boys from Quraysh will come who will withhold this stipend."