The Prophet ﷺ said: “The most beloved of your names to Allah are ʿAbd Allah and ʿAbd al-Rahman” (Muslim 2132), and scholars add to them all names formed on a name of Allah. The name al-Muʾmin occurs 1 times in the Quran; its page in the 99 Names section gives its meaning and verses.
ʿAbd al-Muʾmin joins ʿabd with al-Muʾmin, from the root ʾ-m-n of safety and faith: the One who reassures His creatures, protects them and confirms the truthfulness of His messengers. The name recalls ʿAbd al-Muʾmin ibn ʿAli, the first Almohad caliph, who unified the Maghreb and al-Andalus in the 12th century.
He is Allāh, other than whom there is no deity, the Sovereign, the Pure, the Perfection, the Grantor of Security, the Overseer, the Exalted in Might, the Compeller, the Superior. Exalted is Allāh above whatever they associate with Him.