Mustahabb (Arabic: مُسْتَحَبّ, lit. 'beloved thing') is an Islamic term referring to an action or thing that is recommended and favoured.

Mustahabb actions are those whose ruling (ahkam) in Islamic law falls between mubah (neutral; neither encouraged nor discouraged) and wajib (compulsory). One definition is "duties recommended, but not essential; fulfilment of which is rewarded, though they may be neglected without punishment".^[1] Synonyms of mustahabb include masnun and mandub. The opposite of mustahabb is makruh (discouraged).

Parallels have been drawn between the concept of mustahabb in Islamic law and the concept of supererogatory acts in the Western philosophical tradition.^[2]

There are possibly thousands of mustahabb acts,^[3] including:

• As-Salamu Alaykum (a traditional Islamic greeting) (though responding to the greeting is an obligation)
• Sadaqah (charity outside of zakat)
• Umrah (except in the Shafi'i and Hanbali madhhab, wherein it is fard)

• Ihtiyat Mustahabb
• Makruh
• Supererogation, a similar concept in Western philosophy and religion