Imam Ja‘far al-Ṣadiq (as): The believer's promise made to his fellow brother is a vow for which no amends can be made if broken; so he who breaks a promise has first broken his promise to God and exposed himself to His hatred, as God says in the Quran: "O you who believe! Why do you say what you do not do? It is most hateful to God that you say what you do not do." al-Kāfī