Al-Kāfi - The Book of Belief and Disbelief

Al-Kāfi - The Book of Belief and Disbelief Chapter: Causing Suffering and Disappointment to Parents (al-‘Uquq) َّدُ بْنُ يَحْيَى عَنْ أَحْ٠َّدِ بْنِ عِيسَى عَنْ ٠َّدِ بْنِ سِنَانٍ عَنْ حَدِيدِ بْنِ حَكِي٠ٍ عَنْ أَبِي عَبْدِ الله (عَلَيهِ السَّلا٠) قَالَ أَدْنَى الْعُقُوقِ أُفٍّ وَلَوْ عَلِ٠َ الله عَزَّ وَجَلَّ شَيْئاً أَهْوَنَ ٠ِنْهُ لَنَهَى عَنْهُ.

Had Allah, the Majestic, the Glorious, known anything expressing a lesser degree of disappointment than this ‘Uff, He would have prohibited it.” شهور - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (10/370))