Is wiping the neck (al-'unuq) during ablution required or established by Sunnah?

Primary text

Wiping the neck during ablution is not established through reliable narration from the Prophet, peace be upon him. Imam Ahmad considered wiping the neck to be an addition (ziyada) to the established practice of wiping the head, ears, and implicitly, not the neck, as he did not perform it. Although it is reported that Abu Hurayrah related that the neck is the place of the fetter (al-ghull), this context does not establish it as part of Wudu. Furthermore, a narration stating Imam Ahmad wiped the back of his head (qafa) after wiping his head and ears during Wudu was deemed a mistake (wahm) by Al-Khall.