During an emotional eulogy, Israeli President Herzog expresses regret to the family of the slain American hostage Hersh Goldberg-Polin.

On Monday, Israeli President Isaac Herzog mourned the death of Israeli-American hostage Hersh Goldberg-Polin and expressed regret "on behalf of the state of Israel" for the Hamas-perpetrated killings of six captives over the weekend.

As the President of Israel, I stand here today with a broken heart, bidding farewell to my beloved Hersh and asking for his forgiveness, as well as the forgiveness of Carmel, Eden, Almog, Alex, Ori, and all his loved ones.

"I offer my sincere apologies on behalf of the State of Israel for our failure to protect you during the October 7 disaster, and for not being able to bring you home safely. I am deeply sorry that the country you immigrated to at the age of 7, where you were wrapped in the Israeli flag, could not keep you safe. Rachel, Jon, dear Libby, and Orly, grandparents, and the entire family, I humbly ask for your forgiveness for not being able to bring Hersh back home alive. Your unique light, Hersh, shone brightly and captured all of us from the moment we saw him, even through the posters calling for his return."

"Although many of us did not have the privilege of knowing you in life, you have been alive in us for eleven months now; together with many other brothers and sisters, held captive by cursed, monstrous murderers – since Simchat Torah – which turned into the day of our disaster," he said. "Know this: We are witnesses, and we will never forget. There is no door in the world on which your beloved family did not knock for you, for your rescue and well-being. There is no stone they left unturned, no prayer or plea they did not cry out – from one end of the world to the other – in the ears of God and man."

Mourners were informed by Herzog that Israel has an immediate and pressing responsibility.

The leader emphasized the importance of determination and courage in saving those who can still be saved and bringing back all our sons and daughters, brothers and sisters. He stated that this is not a political goal, but a moral duty of the State of Israel to its citizens.

"We did not fulfill our duty, but now we have a sacred and shared obligation to bring them back to their homeland. For the spirit, resilience, and unity of Israel, Herzog added. We must hold accountable the despicable murderers who butchered Hersh, his friends, our sisters, and our brothers. Our mission is clear and binding: to continue fighting relentlessly against the murderous terrorist organization Hamas, which has once again proven that there is no end to its savagery and the crimes against humanity it is willing to commit."

The funeral for Goldberg-Polin, a 23-year-old Berkeley native who was one of the most well-known hostages, was attended by thousands on Monday, according to The Associated Press. His parents had led a high-profile campaign for the captives' release, meeting with President Biden and Pope Francis and addressing the Democratic National Convention last month.

On Monday morning, Biden returned to the White House from a two-week vacation at Rehoboth Beach, Delaware. He and Vice President Kamala Harris met with a hostage deal negotiating team in the Situation Room following the murder of Goldberg-Polin and five other hostages by Hamas on Saturday.

During Hamas' Oct. 7 attack, Goldberg-Polin, a dual U.S.-Israeli citizen, was seized at a music festival in southern Israel. Israeli forces later recovered his body in the tunnels under Rafah, along with five other Israelis. According to the Israeli military, Hamas terrorists murdered the six hostages as Israeli forces closed in during a rescue mission in Gaza.

On Sunday, U.S. Defense Secretary Lloyd Austin spoke with Israeli Minister of Defense Yoav Gallant, expressing his deepest condolences to the families of the slain hostages and condemning their execution by Hamas. The Secretary emphasized that Hamas leaders must be held accountable for their crimes and reaffirmed his commitment to reaching a ceasefire deal to secure the release of all hostages.

Following the Oct. 7 attacks, Hamas continues to hold 101 hostages, including seven Americans.

The Associated Press contributed to this report.