Chapter on Oaths, Vows, and Expiations
Man Lā Yaḥḍuruh al-Faqīh|Volume 3|Book 2|Chapter 38
وَ قَالَ رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ: "مَنْ حَلَفَ سِرّاً فَلْيَسْتَثْنِ سِرّاً وَ مَنْ حَلَفَ عَلاَنِيَةً فَلْيَسْتَثْنِ عَلاَنِيَةً".
The Messenger of Allah سبحانه وتعالى (peace be upon him and his family) said: "Whoever takes an oath in private should make an exception in private, and whoever takes an oath publicly should make an exception publicly."
- Ṣaḥīḥ al-Faqīh