Family members identified the dead man as Muhammad Odda, 37.
They said Odda was shot and killed shortly after he left his home at 4.30am (0230 GMT) to pray at a nearby mosque.Witnesses said they saw a vehicle fleeing with four masked men inside. No more information was immediately available.
On Tuesday, Fatah's al-Aqsa Martyrs Brigades in the West Bank had threatened to assassinate senior Hamas leaders, though it later reversed the call, encouraging fighters to turn their weapons on Israel instead.
Meanwhile, the Israeli army denied it was involved in the shooting in the town of Habla, which followed several days of deadly violence between Hamas and the rival Fatah Party.