Dying without bequeathing and the heirs giving away Sadaqah from the inheritance

Q: Our father died and bequeathed nothing of the wealth he left behind. He left behind a farm where palm trees are grown. He is not indebted to any person. His pubescent heirs donated a one-third portion of the palm trees and the annex to his farm. They made as Waqf (endowment) out of its produce one or two Ud-hiyahs (sacrificial animals offered by non-pilgrims) to be sacrificed. The remainder of the estate is spent in charitable ways of disposition. Is that donation permissible in the Islamic Shari`ah? Give us your fatwa, may Allah reward and protect you!

A: If the heirs are pubescent and the donation is made out of their own will, it will be effected and they will be granted reward on account of it. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.