Newby, who was being treated for a chest infection at the time, said he approached Farooq outside the maternity ward after spotting him fidgeting and looking anxious.
“He looked out of place so I went over to see if he was alright, to see if I could cheer him up,” he explained.
“He was watching a bag all the time which was six feet away.”
Newby, from Leeds, persuaded Farooq to open it up and show him the contents – a pressure cooker bomb with 10kg of explosives.
A trial at Sheffield Crown Court heard the bomb was estimated to be “double the size” of the device used in the 2013 Boston Marathon attack, which killed three and injured hundreds.
“I thought there’s no way of getting away now so I might as well stay with the guy,” Newby said.
“If I’d have run away he would have panicked.
“I stuck with him, trying to take his mind off what he wanted to do, get to know him and what he was thinking and see if I could change it.”
