رسولُ اللَّهِ صلى اللَّه عليه وآله : مَن كانَ يُؤمِنُ باللَّهِ واليَومِ الآخِرِ فَلْيَفِ إذا وَعَدَ . بحار الأنوار : 77 / 149 / 77 .
The Prophet (SAWA) said, 'He who believes in Allah and the Day of Judgment must fulfil his promise when he promises.' Bihar al-Anwar, v. 77, p. 149, no. 77