1625. Commentary: The aim of the Imam (rahimahullah) is to clarify that using the siwak (tooth-stick) is both an action of the Prophet (sallallahu alayhi wa sallam) and a command from him. Furthermore, this narration is found as marfu‘ (attributed to the Prophet sallallahu alayhi wa sallam), mawquf (attributed to a Companion radi Allahu anhu), and maqtu‘ (attributed to a Successor).
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 1625