400
These two *Old Testament* events contain durations of 40 days or 40 years. (there are a total of 5, only need to name 2)
(1) What are: the Exodus (40 years), (2) Moses receiving 10 commandments, (3) The Great Flood (Noah), (4) Jonah told Ninevah they had 40 days to repent, (5) Elijah's journey to Horeb or Mt Sinai.