Haniyeh made the remarks on Tuesday, shortly after an Israeli drone attack against a southern suburb of the Lebanese capital Beirut led to the martyrdom of six people, including Arouri.
“We mourn the martyrdom of the fighting leader and great national figure, Sheikh Saleh Al-Arouri, as well as Al-Qassam commanders Samir Fandi and Azzam Al-Aqra', and a group of martyrs, following a cowardly Zionist operation in Beirut,” said Haniyeh.
“The Zionist occupation's assassination of leader Al-Arouri and his brothers is a complete act of terrorism and a violation of Lebanon's sovereignty, expanding the scope of its aggression on our people and our nation,” he stated.
“The Nazi-Zionist occupation bears responsibility for this aggression,” he added.
“The pure blood of the martyred leader Sheikh Saleh al-Arouri and his brothers has mingled with the blood of tens of thousands of martyrs of our people in the Gaza Strip, the West Bank, and abroad,” he said.
The Hamas political bureau chief went on to say that “a movement that offers its leaders and founders as martyrs for the dignity of our people and nation will never be defeated.”
“These attacks only strengthen its strength, resilience, and unwavering determination. This is the history of the resistance and the movement: following the assassination of its leaders, it becomes even stronger and more determined,” he said.
Arouri, who used to serve as the deputy head of the Political Bureau of the Gaza Strip-based Palestinian resistance movement of Hamas, was known as the "architect" of the October 7 operation by Gaza's resistance groups, during which hundreds were taken captive.
Meanwhile, the head of the Palestinian Islamic Jihad movement also condemned the Israeli act of terrorism.
In his statement, commander Ziad al-Nakhalah said, “Sheikh Saleh al-Arouri was one of the distinguished and devoted leaders of the Palestinian people.”
“We have lost him when we needed his presence the most. He was a leader who instilled confidence and tranquility in those around him and those he dealt with,” he stated.
“We have lost him as a leader and a person who believed in the justice of the Palestinian people's fight until martyrdom, and he achieved it in the glory of Palestine and the resistance, in its glory that is manifested today in the jihad and heroism of the Palestinian people in Gaza, the West Bank, across Palestine, and beyond. We pray to Allah to accept him graciously," he said.