We should note at the outset that in the era before clocks and precise record keeping, numbers were often an estimation. Three and five signified a little, and forty a lot more. That is not to say that forty was never an accurate number, only that precision was not the intent of biblical authors.
The number forty appears for the first time in scripture in Genesis 7 describing the details of the great flood, which began with forty days and nights of rain and led to the death of “every living creature” (v 4) God had made except the people and animals preserved in the ship constructed by Noah and his sons under God’s direction. The last time forty appears in the Bible is Hebrews 3:10 and 17. There God’s anger with Israel during the four decades in the wilderness after the exodus from Egypt is used to demonstrate the superiority of Jesus over Moses. The author also warns those who have the chance to know Christ not to display hard hearts like those of the people of Israel long ago.
DIVINE JUDGMENT OR TESTING
Between these two examples, the number forty appears in such consistent settings that Christians have long equated it with a trial period or divine judgment, a time of hardship and difficulties.
The Bible notes that Moses stayed up on the mountain of God for forty days while the people waited below on the plain (Exod 24:18). We don’t know how difficult the time was for Moses, but we know that the people got tired of waiting for him and came up with an alternative god, a golden calf, who wouldn’t demand as much as the real God and wouldn’t say anything about whatever behavior they decided to display. Needless to say, their impatience under a forty-day delay was one factor that led to them having to endure a forty-year delay before entering the Promised Land.
The punishment for various transgressions was limited to forty lashes for Israelites (Deut 25:3; 2 Cor 11:24). During the time of the judges, one particularly difficult episode was a forty-year period when Israel was under the domination of the Philistines (Judg 13:1). God raised up Samson to free the people from that bondage. Here again, the forty years was a symbol of God’s punishment and testing.
On a later occasion, the prophet Elijah followed up a brilliant victory over the prophets of Baal by fleeing in terror when Queen Jezebel threatened his life. He ended up in the wilderness with no means of sustenance, so God fed him. He was so energized by the bread and water God provided that he traveled forty days and nights to Mount Horeb, the same place where Moses had spent his time alone with God (1 Kings 19:1-18). His fear of Jezebel had to be thoroughly crushed by an even greater fear of the God who met him on Mount Horeb. The forty-day journey was symbolic of the testing God was causing him to undergo in order to prepare him for greater service.
LASTING IMAGE
During the days of the prophets, Ezekiel created a lasting image by lying on his right side for forty days (Ezek 4:6) to symbolize the years of punishment Judah would experience. And Jonah’s reluctant message finally delivered in Nineveh gave that great city forty days to repent (Jon 3:4). Much to Jonah’s charging, the people heard him and repented.
Alongside the people’s forty-year wandering in the desert, Jesus’ forty-day fast in the wilderness at the outset of his ministry is another recognizable use for his ministry is another recognizable use of the number (Matt 4:2). But the comparisons between the two events go beyond numbers. Jesus’ threefold temptation parallels the trials and failures of God’s people. They, like he, were tempted with food (Exod 16:1-8; Matt 4:3). Satan incited both the people and Jesus to put God to the test (Exod 17:1-3; Matt 4:5-7), and he tempted each of his targets to idolatry (Exod 32; Matt 4:8-10). The people failed; Jesus resisted using passages from Deuteronomy written as Moses led the people in the wilderness.