Hezbollah was preparing a show of strength on Sunday with an elaborate and sprawling funeral for its assassinated leader, Hassan Nasrallah, an event the Iran-backed militant group hopes will revive its battered image in Lebanon after the latest war with Israel.

Tens of thousands of people from across the country and region are expected at the ceremony on Sunday afternoon, including dignitaries from Iran. It will begin at Lebanon’s largest sports stadium on the southern outskirts of the capital, Beirut, which has been adorned with two-story tall posters of Mr. Nasrallah and slogans promising to carry on the Shiite Muslim resistance he led against Israel.

After the stadium service, Mr. Nasrallah will be buried at a dedicated site nearby that will be made into a holy shrine for the slain leader, according to Hezbollah officials.

Mr. Nasrallah’s funeral “is not a day of grief or a day of farewell, but a day of loyalty and renewal of our covenants and pledges to our leader,” Hussein Haj Hassan, a Hezbollah-affiliated member of parliament, said at a ceremony in Beirut’s southern suburbs on Saturday.

He said the funeral would be a moment to show to “allies as well as to our enemies and opponents that we have not and will not weaken or cower.”

“And if you increase the challenge,” Mr. Hassan continued, “we will respond with determination.”

The funeral comes five months after Israel killed Mr. Nasrallah on Sept. 27, dropping 80 bombs over several minutes on his bunker just south of Beirut. In killing Mr. Nasrallah, Israel eliminated a leader who enjoyed near-mythical status among Lebanon’s Shiite Muslims. His death was one of the seminal moments in the confrontation between Iran’s proxies and Israel, which Hezbollah has emerged from significantly weakened.