Forty is a significant number in the Bible. The great flood of Genesis was the result of 40 days of rain (Genesis 7:4). Moses was with God for 40 days receiving the Law (Exodus 24:18). Spies explored the land for 40 days (Numbers 13:25). The Jews wandered in the desert for 40 years (Numbers 32:13). Jonah warned of judgment in 40 days (Jonah 3:4). Jesus was tempted for 40 days as He began His ministry (Luke 4:2), and He appeared to the disciples for 40 days as He concluded it (Acts 1:3). So one Bible teacher suggests that when you see the number 40 in Scripture, it means that God is doing something significant.