The guarantor and the creditor must be of the age of legal responsibility (bāligh), sane (ʿāqil), and no one must have compelled them [to enter into the suretyship agreement]. Furthermore, they must not be foolish with finances (safīh),[2] and the creditor must not have been proclaimed bankrupt (mufallas).
However, these conditions do not apply to a debtor; for example, if a person acts as guarantor for paying off the debt of a child, an insane person, or someone who is foolish with finances, it is valid.