Context it's Monday
I will do it today
Now it's Friday
I want to report this setnce
He said he would do it that day
Ok. That's fine but "that day" it's not specific we don't know when excatly something was said. How to inform someone that is happened on Monday
He said he would do it 5 days before
But it would mean that he said " I will do it 5 days ago" doesn't make sense. Then, how to express it using other way than just saying
He said he would do it on Monday. Is there any other way?