Is an oath permissible regarding a matter upon which testimony is not valid?
General Chapter
Al-Mughni
Book of Testimonies
Primary text
It is permissible for a person to take an oath regarding a matter about which testimony is not valid. An example is finding a debt written in one's own handwriting, knowing the writer only writes the truth, even if the debt was not intentionally mentioned, or finding a debt written in a father's handwriting in his ledger, knowing the father was trustworthy and only wrote the truth. In such cases, one may swear to it, but cannot testify to it. Similarly, if a trustworthy person informed one of the father's debt and one relied upon that information, one may swear to it but not testify to it. This is the view of al-Shafi'i.
Supporting text
The distinction between taking an oath and giving testimony rests on two points. First, testimony is given on behalf of another, which opens the possibility that the documented right may have been forged against the true owner; this is not applicable to one's own oath, as no one can forge a right against the oath-taker. Second, a person frequently writes down their own rights, leading to forgetfulness of some items, unlike testimony.