They may hand over the facilitation to any participant willing to do so.

Like Bernard Marie says. Some Facilitators ask somebody to replace them and some Facilitators do it themselves. This depends on the level of experience and the personal feeling. Mostly I do it myself with own agendapoints so I can use it as a learning opportunity, like name the role, clearly define what pathway (e.g. I want an action from, I want to share information etc.). But no rule on this. Do what feels comfortable.