ما المقصود بالجمل "حتى يسير الراكب من صنعاء إلى حضرموت لا يخاف إلا الله والذئب على غنمه" الواردة في الحديث؟

The aforementioned sentence from the hadith indicates the completion of the matter of Islam and the security of people from aggression, where a person can travel alone safely. It is possible that the Sana'a mentioned is Sana'a of Yemen or Sana'a of ash-Sham. The estimation is: "and he fears nothing but the wolf for his sheep," to illustrate security from human aggression, not from the aggression of a wolf. This hadith exaggerates the achievement of security and the removal of fear.