Al-Kāfi
Hadith 85914- مُحَمَّدُ بْنُ يَحْيَى عَنْ مُحَمَّدِ بْنِ أَحْمَدَ عَنِ الْحَسَنِ بْنِ الْحُسَيْنِ اللُّؤْلُؤِيِّ رَفَعَهُ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) قَالَ قُلْتُ لَهُ الرَّجُلُ يَقُولُ عَلَيَّ نَذْرٌ وَلا يُسَمِّي شَيْئاً قَالَ كَفٌّ مِنْ بُرٍّ غُلِّظَ عَلَيْهِ أَوْ شُدِّدَ.
14. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Hassan ibn al-Husayn al-Lu’lu’iy in a marfu‘ manner who has narrated the following: “I once asked abu ‘Abd Allah (a.s.), about the case of a man who says, ‘There is a vow and commitment on me’, but does not specify. He (the Imam) said, ‘He owes one handful of wheat, regardless, he has taken it seriously or with great emphasis.’”