The money in there should suggest a genuine source.
The source of funds should correlate with your profile.
A banker's salary of 120k a month for 3 years which he has worked totals
N4, 320,000
Assuming his expenditure is half of his salary, it means he only saves 50% per month which totals N2,160,000 in 3 years.
What is the source of the money?
Does he have other sources of income?
Did he make an investment that yielded heavily?
All of these have to reflect in his profile.