Forty is mentioned in the Quran in these verses:

[2:51] Yet, when we summoned Moses for forty nights, you worshiped the calf in his absence, and turned wicked.

[5:26] He said, “Henceforth, it is forbidden them for forty years, during which they will roam the earth aimlessly. Do not grieve over such wicked people.”

[7:142] We summoned Moses for thirty nights, and completed them by adding ten. Thus, the audience with his Lord lasted forty nights. Moses said to his brother Aaron, “Stay here with my people, maintain righteousness, and do not follow the ways of the corruptors.”

[46:15] We enjoined the human being to honor his parents. His mother bore him arduously, gave birth to him arduously, and took intimate care of him for thirty months. When he reaches maturity, and reaches the age of forty, he should say, “My Lord, direct me to appreciate the blessings You have bestowed upon me and upon my parents, and to do the righteous works that please You. Let my children be righteous as well. I have repented to You; I am a submitter.”

To learn more, read the Quran in English.

Want to study the Quran every week? We provide online Friday meetings every Friday.