—the majority hold that such a statement is marfūʿ, and Ibn ʿAbd al-Barr even reported consensus on the point (1). He said: “If someone other than a Companion uses that wording (2), the ruling is the same, so long as he does not attribute it to its particular author—as in the expression ‘the practice of the two ʿUmars.’”
That claim of consensus, however, is open to scrutiny. Al-Shāfiʿī himself voiced two opinions on the matter (3), and those who judged it not to be marfūʿ include: Abū Bakr al-Ṣayrafī among the Shāfiʿīs (4), Abū Bakr al-Rāzī among the Ḥanafīs (5), and Ibn Ḥazm of the Ẓāhirī school (6). Their argument is that the term sunnah may pertain either to the Prophet ﷺ or to someone else.
They were answered (7) that the possibility of intending anyone other than the Prophet ﷺ is remote.
Al-Bukhārī narrates in his Ṣaḥīḥ (8), within (9) the report of Ibn Shihāb (10) from Sālim ibn ʿAbd Allāh ibn ʿUmar—on the authority of his father, in the account (11) of his encounter with al-Ḥajjāj—that he said to him: “If you are truly seeking the Sunnah, (12) …”