Police are appealing for information after the incident on Saturday, March 30, in the South Gyle area on Edinburgh.
The victim, a 71-year-old man, was walking on a footpath to the rear of South Gyle Mains around 8am when he was assaulted and robbed of a four-figure sum of cash.
He suffered injuries to his face in the assault and was taken to the Edinburgh Royal Infirmary for treatment.
The suspect is described as white, 5ft 10ins tall, in his early 20s, clean-shaven, with an athletic build. He was wearing a dark blue hooded top and light blue jeans, with a scarf covering his face.
Detective Inspector Neil Spowart said: “The victim is still in hospital receiving treatment for injuries sustained in this assault, and we are appealing for any information that can help us identify the suspect.
“Anyone who witnessed the assault, or who was in the area of South Gyle Mains on Saturday morning and noticed the suspect there, should contact police.
“Enquiries have suggested that the suspect may also have been in the area early last week, and we want anyone who recognises his description, or who has any other information that can assist our enquiries, to get in touch immediately.”
Anyone with information should contact police on 101, or make an anonymous report through Crimestoppers on 0800 555 111.