Will by a Muslim testator
"Mohammedan Law limits the power of bequests to 1/3 of the net assets. The 2/3 must, in any case be distributed according to the rules of intestacy. The will is prominently referred to as wasiyyat in Mohammedan law. In simple words, a Muslim male cannot will away more than 1/3rd of his estate, i.e. 2/3rd of the property must be divided among the family members in the shares, as laid down in The Shariat Act, 1937. Mohammedan Law gives the male heirs, the sons, twice the share of daughters. There is a provision that heirs of a Muslim testator may consent to bequest in excess to 1/3rd of testator's assets. A Muslim is fully competent to change his Will during his life time or cancel any legacy. A Will made by a Muslim testator may be treated as void, if a testator after making a Will, turns out to be of unsound mind and continues to be so till his death."
(p. 10, 'Making a Will Made Easy' by V. K. Verma – Macmillan)