Chapter on Oaths, Vows, and Expiations
Man Lā Yaḥḍuruh al-Faqīh|Volume 3|Book 2|Chapter 38
وَ رَوَى اَلسَّكُونِيُّ عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ عَلَيْهِ اَلسَّلاَمُ قَالَ: "إِذَا قَالَ اَلرَّجُلُ أَقْسَمْتُ أَوْ حَلَفْتُ فَلَيْسَ بِشَيْءٍ حَتَّى يَقُولَ أَقْسَمْتُ بِاللَّهِ أَوْ حَلَفْتُ بِاللَّهِ".
Al-Sakuni narrated from Imam Jafar ibn Muhammad Al-Sadiq عليه السلامwho said: "If a man says, 'I swear' or 'I have taken an oath,' it is of no consequence until he says, 'I swear by Allah سبحانه وتعالى' or 'I have taken an oath by Allah سبحانه وتعالى.'"
- Ṣaḥīḥ al-Faqīh