Sunan Abi dawud:1661 Chapter: Zakat Book 9, Hadith 106

The aforesaid tradition has also been transmitted by ‘Ubaid bin ‘ Umair through a different chain of narrators. This version goes: A man asked: Messenger of Allah (ﷺ), what is due on camels? He replied in a similar way. This version adds “and to lend its udders.”