On it being disliked to ride a camel that eats dung. If it then eats pure fodder and its flesh is wholesome, then the dislike is removed

Riyad as-Salihin (The Meadows of the Righteous)

by Imam Nawawi

308. Chapter: On it being disliked to ride a camel that eats dung. If it then eats pure fodder and its flesh is wholesome, then the dislike is removed

1692. Ibn 'Umar said, "The Messenger of Allah, may Allah bless him and grant him peace, forbade riding camels that eat dung." [Muslim]