If two routes give “Zayd ʿan Khālid” and a third “Zayd ʿan Bakr ʿan Khālid,” which possibilities must be investigated?

The Muqaddimah’s Aim: Mastery, Selection, and Critical Comparison

• Two shorter routes automatically prove the extra intermediary mistaken
• Examine possible omission, mistaken insertion, or genuine hearing by both routes
• An extra intermediary makes the shorter routes disconnected without further inquiry
• The number of routes conclusively establishes connection without hearing evidence