Mr Marriott was out for a post-Christmas walk with his wife and sons when he stopped to help Nafeesa Jhangur who lay injured.
He was one of five people hit by a car driven by Ms Jhangur’s brother, Hassan, Sheffield Crown Court was told.
Prosecutors said Jhangur ploughed into them and three other people in the Burngreave area, before getting out of the vehicle and attacking another man with a knife, leaving him with serious injuries.
The man Jhangur stabbed a number of times after the car crashed – Hasan Khan – had married the defendant’s sister Amaani earlier on the same day.
Jhangur told his trial he lost control of the car as he went round a corner and did not intend to hurt those he hit. He said he stabbed Mr Khan as he defended himself when he came under attack.
After a week of deliberations, the jury was discharged after failing to reach any verdicts.
On Monday, a hearing at Sheffield Crown Court fixed a date for the retrial.
