Mustahabb (Arabic: مُسْتَحَبّ, lit. 'beloved thing') or Mandub (Arabic: المندوب, lit. 'delegate') 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". 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.
In the principles of Islamic jurisprudence (Arabic: أصول الفقه, romanized: uṣūl al-fiqh), rulings governing actions fall into categories known as "the five rulings" (الأحكام الخمسة, al-aḥkām al-khamsa).
It is a sin or a crime to perform a forbidden action or not to perform a mandatory action. Avoiding reprehensible acts and performing recommended acts is held to be subject of reward in the afterlife, while allowed actions entail no judgement from God.
Islamic jurists disagree on whether the term halal covers the first two, three, or four of these categories.
There are possibly thousands of mustahabb acts, including: