Is using the Siwak (miswak) obligatory or merely recommended?
Chapter on Siwak and the Sunnah of Wudu
Al-Mughni
Book of Purification
Primary text
Using the Siwak is a confirmed Sunnah (recommended practice) and is not obligatory (wajib). The majority of scholars hold this view. Evidence for its recommendation includes the Prophet's statement that he would have commanded it with obligation if it were not a hardship upon his Ummah (community), indicating that commands not associated with hardship are generally recommendatory. Furthermore, it is considered a confirmed Sunnah due to the Prophet's continuous practice, encouragement, and labeling it as part of the natural disposition (Fitra). Supporting narrations include the Hadith: "The Siwak is a purification for the mouth and pleasing to the Lord" (reported by Imam Ahmad), and Aisha's report that the Prophet would begin with the Siwak upon entering his home (reported by Muslim).
Supporting text
A minority opinion, held by Ishaq and Dawud, suggests that the Siwak is obligatory because the command for it implies obligation. Another view suggests that the obligation might have been specific only to the Prophet, reconciling differing narrations.