Is it permissible for a man to perform the Hajj obligation using his wife's money, given his inability to repay her later?

There is no disagreement that no time limit is set for the repayment of a loan. The majority of scholars believe that postponing the repayment of a loan is invalid and does not obligate the lender to fulfill it; rather, the lender may reclaim the loan before the specified term. The Malikis, however, hold that postponing a loan is binding if it was stipulated at the time of the contract; otherwise, it is determined by custom. This is the more preponderant view, which was favored by Sheikh al-Islam Ibn Taymiyyah, due to the generality of the hadith (definition): "The Muslims are bound by their stipulations."