Is it permissible for one of the heirs to waive his share of the inheritance to the other heirs for financial compensation, prior to the distribution of the estate and its details, with his desire to waive his entire share of all that the deceased left behind? Or must the estate be distributed first, and then he waives his share?

If the heirs agree to exclude some of them from the division in exchange for a known amount, this is permissible with their mutual consent. Abd al-Rahman ibn Awf narrated that Uthman inherited from Tumadir al-Kalbiyyah along with three other women. They reconciled with him over a quarter of her thumn (an eighth share) for eighty-three thousand [dirhams]. Among the conditions for the validity of takharuj (mutual exclusion from inheritance) is that the inheritance be known, as takharuj is often a sale in the form of a reconciliation, and selling the unknown is not permissible. However, if it is impossible to know the inheritance, then in this case, reconciliation over the unknown is permissible according to the Malikis, Shafi'is, and Imam Ahmad. As for the Hanafis, it is not a condition that the specific assets of the inheritance be known in matters that do not require possession. Therefore, takharuj over an unknown inheritance is not permissible according to the majority of scholars.