Mustahabb is an Islamic term referring to recommended, favoured or virtuous actions.
Mustahabb actions are those whose ruling in Islamic law falls between mubah and wajib. One definition is "duties recommended, but not essential; fulfilment of which is rewarded, though they may be neglected without punishment". Synonyms of mustahabb include masnun and mandub. The opposite of mustahabb is makruh.
Parallels have been drawn between the concept of mustahabb in Islamic law and the concept of supererogatory acts in the Western philosophical tradition.