What is the reason for the number 40 to be mentioned so many times in the Bible?
I am not sure why God chose to use that number so often. It rained 40 days and nights during the flood. Genesis 7:12 says, “And the rain was upon the earth forty days and forty nights.”
Isaac was forty when he got married. Genesis 25:20 says, “And Isaac was forty years old when he took Rebekah to wife.” Their son Esau was also 40 when he got married to his first wives. Genesis 26:34,35 says, “And Esau was forty years old when he took to wife Judith the daughter of Beeri the Hittite, and Bashemath the daughter of Elon the Hittite: Which were a grief of mind unto Isaac and to Rebekah.”
Moses was forty when he thought he was ready to lead. Acts 7:22-25 says, “And Moses was learned in all the wisdom of the Egyptians, and was mighty in words and in deeds. And when he was full forty years old, it came into his heart to visit his brethren the children of Israel. And seeing one of them suffer wrong, he defended him, and avenged him that was oppressed, and smote the Egyptian: For he supposed his brethren would have understood how that God by his hand would deliver them: but they understood not.”
The spies searched the Promised Land for 40 days. Numbers 13:25 says, “And they returned from searching of the land after forty days.”
I do not worry too much about searching for some deeper meaning in numbers, whether it be the number 40, or the number 7. I Timothy 1:4 says, “Neither give heed to fables and endless genealogies, which minister questions, rather than godly edifying which is in faith: so do.” That is the same problem with searching for deeper meaning in numbers — it only ministers questions, rather than godly edifying. What we need to do is just make every day count for God. Psalm 90:12 says, “So teach us to number our days, that we may apply our hearts unto wisdom.”