The hours passed in fruitless speculation on one side of the room and loud snoring on the other.
Whether he would have done the right thing by her - as they said in those days - is fruitless speculation: he was never told of the need.
A great deal of fruitless speculation will be devoted to trying to read the minds of the jurors.
This was no time for fruitless speculation.
He refused even to waste odd moments of the night on such fruitless speculation.
Anger gives way to fruitless speculation.
It caused a commotion of acclaim, ringing cash tills and fruitless speculation as to my secret.
It was unwise to engage in fruitless speculation.
Satan, who finds work for idle hands to do, also fills idle minds with fruitless speculation.
What I know or do not know does not concern you, so do not tax your brain with fruitless speculation.