Question: "What is the significance of '40 days' in the Bible?"
Answer: The number 40 shows up often in the Bible. Because 40 appears so often in contexts dealing with judgment or testing, many scholars understand it to be the number of “probation” or “trial.” This doesn’t mean that 40 is entirely symbolic; it still has a literal meaning in Scripture. “Forty days” means “forty days,” but it does seem that God has chosen this number to help emphasize times of trouble and hardship.
Here are some examples of the Bible’s use of the number 40 that stress the theme of testing or judgment:
In the Old Testament, when God destroyed the earth with water, He caused it to rain 40 days and 40 nights (Genesis 7:12). After Moses killed the Egyptian, he fled to Midian, where he spent 40 years in the desert tending flocks (Acts 7:30). Moses was on Mount Sinai for 40 days and 40 nights (Exodus 24:18). Moses interceded on Israel’s behalf for 40 days and 40 nights (Deuteronomy 9:18, 25). The Law specified a maximum number of lashes a man could receive for a crime, setting the limit at 40 (Deuteronomy 25:3). The Israelite spies took 40 days to spy out Canaan (Numbers 13:25). The Israelites wandered for 40 years (Deuteronomy 8:2-5). Before Samson’s deliverance, Israel served the Philistines for 40 years (Judges 13:1). Goliath taunted Saul’s army for 40 days before David arrived to slay him (1 Samuel 17:16). When Elijah fled from Jezebel, he traveled 40 days and 40 nights to Mt. Horeb (1 Kings 19:8).
The number 40 also appears in the prophecies of Ezekiel (4:6; 29:11-13) and Jonah (3:4).
In the New Testament, Jesus was tempted for 40 days and 40 nights (Matthew 4:2). There were 40 days between Jesus’ resurrection and ascension (Acts 1:3).
Whether or not the number 40 really has any significance is still debated. The Bible definitely seems to use 40 to emphasize a spiritual truth, but we must point out that the Bible nowhere specifically assigns any special meaning to the number 40.
Some people place too much significance on numerology, trying to find a special meaning behind every number in the Bible. Often, a number in the Bible is simply a number, including the number 40. God does not call us to search for secret meanings, hidden messages, or codes in the Bible. There is more than enough truth in the plain words of Scripture to meet all our needs and make us “complete and thoroughly equipped for every good work” (2 Timothy 3:17).