A few days
A few days is just a fancy way of saying ‘I have no idea when I’ll be back.’ It’s like a lie wrapped up in a time frame.
"I'll be back in a few days," he said. He didn’t come back for a few months.
"A few days later, the situation was still bad, but at least it was the same kind of bad this time."
"I said I'd be back in a few days. I was back in a few days, but also in a few hours, and also in a few minutes."