Musnad Ahmad 536:2

Yahya ibn Sa'id narrated to us, from Isma'il ibn Abi Khalid, who said: Qays narrated to me, from 'Adi ibn 'Amirah al-Kindi, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "O people, whoever among you we employ for a task, and he conceals from us a needle or anything above it, then it is misappropriation (ghulul), which he will bring on the Day of Resurrection." He said: Then a black man from the Ansar stood up—Mujalid said: He is Sa'd ibn 'Ubadah—as if I am looking at him, and he said: "O Messenger of Allah, take back your task from me." He said: "And why is that?" He said: "I heard you say such and such." He said: "And I say that now: whoever we employ for a task, let him bring its little and its much. Whatever he is given from it, he shall take, and whatever he is forbidden from, he shall refrain."