“I once asked abu al-Hassan (a.s.), saying, ‘I pray to Allah to keep my soul in service for your cause, people who live in the mountains cut off the tails of their sheep because they become very large.’ He (the Imam) said, ‘It is not lawful (inedible).’ I then asked, saying, ‘I pray to Allah to keep my soul in service for your cause, can it be used in lamps for lighting during the night? He (the Imam) said, ‘You must take notice that it can come in contact with your hand and clothes and it is unlawful.’”