In Sahih Muslim, it is related from Abū Hurayrah [may Allah be pleased with him] (1) that the Prophet—may Allah bless him and grant him peace—said:
“Whoever withdraws from obedience, separates from the united Muslim community, and then dies has died a death of the Age of Ignorance. Whoever is killed under a banner of blind partisanship—becoming angry for a faction, calling to a faction, or supporting a faction (2)—his death is a death of the Age of Ignorance. And whoever rises against my Ummah, (striking both its righteous and its wicked, sparing none of its believers, and failing to honor the covenant of anyone under covenant (3), is not of me) (4), and I am not of him.” (5)
He thus condemned withdrawing from obedience and separating from the united Muslim community, and deemed such a death to be a death of the Age of Ignorance, because the people of the Age of Ignorance had no leader to unite them.
The Prophet—may Allah bless him and grant him peace—consistently commanded that a leader be appointed. He even commanded this while traveling when there were only three people, thus requiring leadership among the smallest number and during the briefest gathering.
In Sahih Muslim, Hudhayfah—may Allah be pleased with him—related:
“I said, ‘O Messenger of Allah, we were living in ignorance and evil, and then Allah brought us (6) this good. Will there be, after…”