Muhammed Saleem, 75, died in a hospital late Monday, about half an hour after the attack, the Daily Mirror reported. His wife, Said Begum, found him in the street.
His son, Shahid, said his father's bank card and cash were still in his pocket and there seems no motive for the attack.
"We cannot understand why anyone would want to do this to a defenseless old man. It was such a vicious attack," he said.
"My dad could barely walk without his stick. He didn't stand a chance of defending himself."
Saleem prayed five times daily at a mosque near his home. Investigators said he was stabbed four times in the back and then, as he lay bleeding in the street, his head was stamped on.