Salim bin Hayyan said:
I heard Abu Hurairah say: "I grew up an orphan, and I emigrated as a poor man, and I was hired by the daughter of Ghazwan in return for food and a turn riding the camel. I would gather firewood for them when they stopped to camp and urge their camels along for them by singing when they rode. Praise is to Allah (SWT) who has caused His religion to prevail and has made Abu Hurairah an Imam."
English reference: Vol. 3, Book 16, Hadith 2445
Arabic reference: Book 16, Hadith 2539