Imam Maalik مالك بن أنس بن مالك بن أبي عامر · The Book of al-Fara' and al-'Atirah

"O Messenger of Allah! (What about) the Fara'?" He said: "It is a duty, but if you leave it (the animal) until it becomes half-grown and you load upon it (in Jihad) in the cause of Allah or give it to a widow, that is better than if you slaughter it (when it is just born) and its flesh is difficult to separate from its skin, then you turn your vessel upside down (because you will no longer be able…

"We are attacking the Maghrib, and they are people who worship idols, and they have waterskins in which they keep milk and water." Ibn 'Abbas said: "Tanning is purification." Ibn Wa'lah said: "Is this your own opinion, or something that you heard from the Messenger of Allah?" He said: "No, (I heard it) from the Messneger of Allah."

"The letter of the Messenger of Allah was read to us when I was a young boy: 'Do not make use of the skins and sinew of dead animals."'