All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The Maaliki scholars held different views regarding Sujood As-Sahw; some of them held that it is obligatory (Waajib), and others held that it is an act of the Sunnah (optional). The difference of opinion among the Maaliki scholars has been underlined by the well-versed scholar Al-Hattaab in his book Mawaahib Al-Jaleel:
“Scholars differed regarding the ruling on Sujood As-Sahw and whether it is to be performed before or after the Tasleem. As for Sujood As-Sahw before the Tasleem, some maintained that it is an act of the Sunnah, and this view was adopted by Ibn ‘Abd Al-Hakam. Others, such as Al-Maaziri, based on the view that missing it invalidates the prayer, held that it is obligatory (Wajib). Other scholars believed that it is obligatory in case the worshiper forgets three acts of the Sunnah in the prayer and that it is an act of the Sunnah (optional) in case he forgets two acts of the Sunnah in the prayer. As for Sujood As-Sahw after the Tasleem, ‘Abd Al-Wahhaab and Al-Maaziri held that it is an act of the Sunnah. Another scholarly view suggests that it is obligatory, as was cited in At-Tiraaz (book). Thus was the difference of opinion narrated on the authority of Ibn 'Arafah, and it was quoted from him by Ibn Naaji in Sharh Al-Mudawwanah.”
Is performing Sujood As-Sahw before the Tasleem an act of the Sunnah or is it obligatory? There are two views in the Maaliki school in this regard; that it is a Sunnah (which is the preponderant view), and that it is obligatory. Al-Basaati underlined that most of the texts and statements of the Maaliki scholars held that it is obligatory.
The author held that the preponderant view in this regard is that Sujood As-Sahw before or after the Tasleem is an act of the Sunnah, and there is no difference of opinion among scholars in this regard. Regarding Sujood As-Sahw after the Tasleem, there is no discussion regarding its preponderance; rather, the discussion is about proving the opposite. Regarding Sujood As-Sahw before the Tasleem, the author relied on the statement of Ibn ‘Abd As-Salaam in this regard and held that the preponderant view is that it is an act of the Sunnah. The author of Sharh underlined that it is the famous view, and so did Al-Aqfahsi and a group of scholars. Ibn Al-Karoof settled for citing the view that it is obligatory. The author of Ash-Shaamel (book) said, “Is Sujood As-Sahw before Tasleem an act of Sunnah? This is what was held preponderant. Or rather is it obligatory? This is the corollary ruling from the evidences of the Mathhab. These are two opinions in the Maaliki School. The Bisaati said: Most of their (the Maaliki scholars') statements indicate that it is obligatory.” [End of quote]
Hence, the Maalikis held that Sujood As-Sahw is either obligatory or an act of the Sunnah (performed by the Prophet, sallallaahu ‘alayhi wa sallam, but not regularly and persistently). We could not find any statement of Maaliki scholars suggesting that it is just Mustahab (recommended).
Allaah knows best.