خَطَأٌ فِي الِاجْتِهَادِ
An error in considered judgment.
Imagine that a major crime occurs while public order is fragile. The demand for justice can be sound, yet there may be disagreement over the sequence of action: secure order first, or pursue immediate punishment? This is a conceptual illustration, not a reconstruction of every historical detail.
The fact that parties spoke of retribution does not erase their disagreement. The practical issue was which course of action would secure justice without intensifying disorder.