Bismillahi Al-Rahmani Al-Rahim

Leather (From Bidayat Al-Mujtahid)

Isa Martin has provided the following, taken from the English translation of Bidayat Al-Mujtahid (vol. 1 p.84-85):
The reason for their disagreement is the conflict of traditions on this issue.  The absolute permissibility of it's utilization is laid down in Maymuna's  (God be well pleased with her) tradition, when the Prophet (God's peace and blessings be upon him) was passing by a carcass he said, 'Would that you had made use of its skin.'  Its absolute prohibition is derived from the tradition of Ibn 'Akim (God be well pleased with him), which states that 'The Messenger of Allah (God's peace and blessings be upon him) wrote that neither its hide nor its sinew are to utilized.'  This was a year before his death.

In some traditions the command conveys (the permissibility of) their utilization after tanning, but not before.  The established tradition for this is that of Ibn Abbas that the Prophet (God's peace and blessings be upon him) said, 'When the hides are tanned they become  purified.'  The conflict of these traditions led the jurists to differ in their interpretation.

One group adopted the method of reconciliation on the basis of  the tradition of Ibn Abbas (God be well pleased with him), distinguishing between tanned and untanned skins. 

Another group adopted the method of abrogation, and relied on the tradition of Ibn 'Akim (God be well pleased with him), because they date it as late as one year before the Prophet's death.

A third group preferred Maymuna's tradition maintaining that it entails an addition over the tradition of Ibn Abbas,as the prohibition prior to tanning cannot be derived from Ibn Abbas's tradition, which speaks of purity, but utilization is different from purification (God be well pleased with them all). While each pure thing may be utilized, it is not necessary that each usable thing is pure.

[end, with minor changes]