Deuteronomy 9:11 And at the end of forty days and forty nights the Lord gave me the two tablets of stone, the tablets of the covenant.
Deuteronomy 9:18 Then I lay prostrate before the Lord as before, forty days and forty nights. I neither ate bread nor drank water, because of all the sin that you had committed, in doing what was evil in the sight of the Lord to provoke him to anger.
Forty is a significant number with meaning in the bible. The first significant effort by man, Moses, was a period of prostrating himself before God twice.
Two is the number of division. It is the first number that can be separated evenly.
The significance of forty began with two parts. The first event is in the giving of the law by God to Moses.
The second significant event is Moses interceding for Israel because of their sinning by turning the gold they had into a calf idol to be worshipped.
Israel violated the first commandment even before it was given to them.
Sin existed before law. Intercession began after the law was violated.
Are we celebrating the significance of forty days or intercession?