Narrated Buraydah ibn al-Hasib: The Prophet ﷺ said: He who swears by Amanah (faithfulness) is not one of our number.
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
Iman (faith) or amanah (trust) are matters obligated by Allah.
There is no meaning in swearing an oath by them; therefore, it is impermissible.
However, according to Imam Shafi‘i rahimahullah, there is no expiation (kaffarah) for this.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 3253