Ayman al-Zawahiri, al-Qaeda's second in command, has issued a eulogy for Osama bin Laden, saying the slain group's chief terrified the US when he was alive and would continue to do so in death. Al-Zawahiri appeared in a white Arab robe and turban, a Kalashnikov at his side, in a 28-minute video posted on jihadist online forums on Wednesday. "We will pursue the jihad until we expel the invaders from Muslim lands," he was quoted as saying in the video titled "The Noble Knight Dismounted". The Egyptian, who has long been considered al-Qaeda's operational head, heaped praise on bin Laden, killed in a May 2 US raid in Pakistan.