Prince Charles has met with the imam hailed as a hero for protecting the suspect in the Finsbury park attack from an angry mob on a visit to the site.
The royal passed on a personal message of sympathy from the Queen as he spoke with faith leaders and community members near the site where Muslim worshippers were struck by a van as they left evening prayers.
One man died and nine people were taken to hospital after the attack in the early hours of Monday.
He praised Mr Mahmoud's "remarkable actions on that terrible occasion", adding "Thank goodness we have wonderful leaders."
The Prince also shared a personal message of "thoughts and prayers" from the Queen.
She has specifically asked me to tell you how shocked she was by what happened, particularly as the victims were worshippers who had been attending Ramadan prayers . Her Majesty's thoughts and prayers are with you all.
Charles stopped to read some of the hundreds of messages of support and anguish left at the site of the attack.
One colourful poster, decorated with glitter hearts and flowers and signed with many names simply asked: "Where's the love?"
Another image showed cut-out figures holding hands around a dove, symbolising peace, while white butterflies adorned the wall above the nearby bouquets.
"Are you sure you should be here?", he asked the 45-year-old, who was on crutches and had his right leg in a cast.
Leaning heavily on crutches, Mr Hersi said he was grateful the prince had visited because it showed people cared "from top to bottom".
He said: "He's been really sympathetic and very sorry for what happened to us, very supportive."