The last known photos of Iranian General Qassem Soleimani show him kissing the forehead of a Hezbollah chief days before he was assassinated by the US.
General Soleimani, head of Iran's elite Quds Force, was seen smiling as he embraced Hezbollah's Secretary-General Hassan Nasrallah during a meeting in Beirut.
The military chief is also seen praying in the images - understood to have been taken last week - which were released by Iranian media on Sunday.
Secretary-General Nasrallah has vowed to avenge his friend's death, saying US forces would "pay the price" for the drone strike that killed General Soleimani near Baghdad's airport last Friday.
He said in a televised speech: "The American army killed them and it will pay the price.
"The only just punishment is (to target) American military presence in the region: US military bases, US warships, each and every officer and soldier in the region."
He said US civilians, including businessmen, engineers, journalists and doctors, should be spared.
He added: "When the coffins of American soldiers and officers... start to return to the United States, (US President Donald) Trump and his administration will realise they have lost the region."
The Hezbollah leader also called on Iraq to free itself of the American "occupation".
Hezbollah has been deemed a terrorist organisation by the US, UK and the Arab League.
General Soleimani was killed in a strike on his convoy after landing at Baghdad's airport, sending the Iran-US conflict into unprecedented territory amid a spiralling crisis.
Iraqi militia leader Abu Mahdi al-Muhandis was also killed.
Prime Minister Boris Johnson, meanwhile, has finally broken his silence on the strike and the growing crisis in the Middle East following his Caribbean holiday.
The PM had faced criticism over his silence and his refusal to cut short his trip to Mustique.
In a statement released on Sunday evening, Mr Johnson did not condemn Mr Trump's actions, saying: "Today I have spoken with President Macron, President Trump and Chancellor Merkel, and will be speaking with other leaders in the coming days.
"General Qassem Soleimani posed a threat to all our interests and was responsible for a pattern of disruptive, destabilising behaviour in the region.
"Given the leading role he has played in actions that have led to the deaths of thousands of innocent civilians and western personnel, we will not lament his death.
"It is clear however that all calls for retaliation or reprisals will simply lead to more violence in the region and they are in no-one's interest.
"We are in close contact with all sides to encourage de-escalation.
"I will be speaking to other leaders and our Iraqi friends to support peace and stability."
It emerged that Iraqi President Barham Salih offered his condolences to Iranian President Hassan Rouhani over the killing and urged self restraint.
The phone call came after Iraq's parliament backed a recommendation by the prime minister that all foreign troops should be ordered out of the country.
Britain has urged Iraq to allow UK soldiers to continue the fight there against the so-called Islamic State terror group following the non-binding vote.
Some 400 UK troops are stationed in Iraq in the fight against IS, while the US has 5,200, prompting fears of a withdrawal that could cripple the battle against the terror group.