10. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn Ahmad ibn ‘Isa from abu al-Qasim al-Sayqal who has said the following
“I once wrote to him (the Imam) (a.s.), and asked, ‘There is a certain sheathing of swords called al-Safan (sandpaper) which is from skin of fish; if it is permissible to work with and we do not eat its meat.’ He (the Imam) wrote back, ‘It is not unlawful.’”