Al-Kāfi - Volume 7 > The Undesirability of Swearing
Hadith #2

2- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ النَّوْفَلِيِّ عَنِ السَّكُونِيِّ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) قَالَ قَالَ رَسُولُ اللهِ (صَلَّى اللهُ عَلَيْهِ وَآلِه) مَنْ أَجَلَّ اللهَ أَنْ يَحْلِفَ بِهِ أَعْطَاهُ اللهُ خَيْراً مِمَّا ذَهَبَ مِنْهُ‏.

2. Ali ibn Ibrahim has narrated from his father from al-Nawfaliy from al-Sakuniy who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said that the Messenger of Allah, O Allah, grant compensation to Muhammad and his family worthy of their services to Your cause, has said, ‘One who delays in swearing by Allah, He grants him better than what he has lost because of the delay.’”