Al-Kāfi
Hadith 86722- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ هَارُونَ بْنِ مُسْلِمٍ عَنْ مَسْعَدَةَ بْنِ صَدَقَةَ قَالَ سَمِعْتُ أَبَا عَبْدِ اللهِ (عَلَيْهِ السَّلام) وَسُئِلَ عَنِ الرَّجُلِ يَحْلِفُ بِالنَّذْرِ وَنِيَّتُهُ فِي يَمِينِهِ الَّتِي حَلَفَ عَلَيْهَا دِرْهَمٌ أَوْ أَقَلُّ قَالَ إِذَا لَمْ يَجْعَلْ للهِ فَلَيْسَ بِشَيْءٍ.
22. Ali ibn Ibrahim has narrated from Harun ibn Muslim from Mas’adah ibn Sadaqah who has narrated the following: “I once heard abu ‘Abd Allah (a.s.), saying, when he (the Imam) was asked about the case of a man who took an oath to make a vow and commitment and his intention in his oath is about one dirham or less. He (the Imam) said, ‘If he has not made it for Allah, then it does not have any valid effect.’”