Sahih Bukhari
Asking Permission
Volume: 008 / Book Number: 074 / Hadith Number: 290
Narrated Abu Bakra:
Allah's Apostle said, "Shall I inform you of the biggest of the great sins?" They said, "Yes, O Allah's Apostle!" He said, "To join partners in worship with Allah, and to be undutiful to one's parents. "