Abu Dawud Book 11, Hadith Number 2869.

Chapter : Gravity of consuming the property of an orphan by the executer.

Narated By ‘Umar ibn al-Khattab : A Companion of the Prophet (PBUH) said: A man asked him (the Prophet): Apostle of Allah, what are the grave sins? He replied: They are nine. He then mentioned the tradition to the same effect. This version adds: “And disobedience to the Muslim parents, and to violate the sacred House, your qiblah (direction of prayer), in your life and after death.