Abdul Malik bin Aby عبد الملك بن أبي سليمان · The Book of Zakah

"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."'