Sunan an-Nasa'i 2449

Bahz bin Hakim narrated from his father that his grandfather said:"I heard the Messenger of Allah say: 'With regard to grazing camels, for every forty a Bint Labun. No differentiation is to be made between camels when calculating them. Whoever gives it seeking reward will be rewarded for it. Whoever refuses, we will take it and half of his camels, as one of the rights of our Lord. And it is not permissible for the family of Muhammad to have any of them