In a discussion with Peter Leithart, we realized that the daily manna provided in the wilderness which the Israelites were prohibited from saving means that Israel was in effect prevented from having leavened bread for forty years. In this sense, the forty years in the wilderness were an extended Feast of Unleavened Bread.
If I may be allowed a Lenten application, this is at least one way of looking at the 40 days of Lent, an extended “feast” which is kept through the practice of getting rid of the old leaven. This is the feast that Christians are called to all the time, every day, “not with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth” (1 Cor. 5:8).