He would not name a successor

Umar had been given the leadership by Abu Bakr, directly. As he lay dying, people asked him to do the same — to name the man who would lead after him.

He refused to.

What he did instead was name a small council of senior Companions and leave the choice to them, with instructions to reach a decision within a set number of days. He would not put his own son in the group as a candidate.

The council chose Uthman ibn Affan.

This is a quiet moment, and easy to skip past. But it is one of the few times in the whole period where somebody with complete authority deliberately declined to use it — and it set a precedent that the community argued about for a long time afterwards.