You ask it, we have it answered!
How much can I bequeath?
The sum of all bequests may not exceed one-third (1/3) of the state. One-third of the state was the maximum allocation allowed by the Prophet, may peace be upon him.
When Saad Ibn Abi-Waqqas (May Allah be please with him) consulted the Prophet (May peace be upon him) about giving two-thirds of his money to charity, the Prophet (May peace be upon him) rejected the two-thirds suggestion and when Saad (May Allah be please with him) then suggested one half, the Prophet (May peace be upon him) rejected that too. Finally, Saad (May Allah be please with him) suggested one-third, which the Prophet (May peace be upon him) reluctantly approved. He said, “A third then, and a third is a lot.”