A Companion may say: «سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ كَذَا»
“I heard the Messenger of Allah ﷺ say such-and-such.”
Equivalent explicit forms include “the Messenger of Allah related to us,” “the Messenger of Allah said,” and “from the Messenger of Allah ﷺ that he said ….” They directly attribute speech to the Prophet.
If a later narrator uses an attribution formula while a link is uncertain, the status of the isnād still requires investigation. What makes the content explicitly marfūʿ is the clear Prophetic attribution, not a guarantee that every link has already been verified.