A man claiming to be Deif, a chief of Hamas' armed wing the Izz al-Din al-Qassam Brigades, urges Palestinians not to halt the struggle against Israel following the evacuation of more than 8000 Jewish settlers from Gaza and small parts of the West Bank.
Deif, accused by Israel of masterminding a long list of attacks, is a mysterious figure who rarely reveals himself in public. Few images exist of him.
"We tell the Zionists who have tarnished our soil, we tell you that all of Palestine will become a hell," he said in the video posted on the internet purportedly by the Brigades on Thursday.
"Today you have left the hell of Gaza in shame but who have not got out completely as you continue to occupy Palestine," he said, urging Palestinians in the West Bank and Jerusalem to continue the armed struggle.
Deif, who has topped Israel's most wanted list for years, has survived multiple attempts on his life, including a rocket attack on his car in Gaza City two years ago.
"We tell the Zionists who have tarnished our soil, we tell you that all of Palestine will become a hell"
He is accused of masterminding a string of bombings in 1996 that killed dozens of Israelis and led to the right's resurgence in Israeli politics. He is also accused of having captured and murdered several Israeli soldiers in the early 1990s.
A successful attack against Deif would be a major blow for Hamas' armed wing.
Meanwhile, Deif also reaffirmed his organisation's vehement rejection of appeals by Palestinian President Mahmoud Abbas for Hamas and other armed factions to disarm after Israel's pullout from the Gaza Strip.
"To the brothers of the Palestinian Authority, the liberation of Gaza has been realised thanks to the sincere actions of the Mujahidin, and as a consequence our weapons will stay in our hands," he said in the video.
"We warn all those who try to touch the weapons of those who liberated Gaza: These arms must be used to free our occupied motherland," Deif added.
"We warn all those who try to touch the weapons of those who liberated Gaza: These arms must be used to free our occupied motherland"
Deif succeeded Yehya Ayash, the former Hamas bomb-maker known as "The Engineer", who is thought to have introduced the deadly tactic of bombings to the Israeli-Palestinian conflict.
Ayash was died in Gaza City on 5 January 1996 when his mobile phone exploded in a blast which was triggered by a phone call.
Deif, 39, became the most prominent Hamas fighter in July 2002 after Israel assassinated Salah Shehade, leader of the Izz al-Din al-Qassam Brigades.