The word for "sign" in verse 9 is 'owth, which can be translated as signal, flag, beacon, monument, omen, prodigy, evidence, mark, miracle, sign, or token. The word for "memorial" is zikrown, meaning memorable thing, reminder, remembrance. If we change "sign" to one of the other translations, it puts this section in a new light. For instance, 'owth can be translated as "prodigy," which means "something extraordinary"!
Verse 9 could be paraphrased, then, "And this observance of the days of Unleavened Bread shall be something extraordinary for you to do, to make a memorable impression on your mind so that the law of God can be written in your hearts."
How do we look at the Days of Unleavened Bread? Are they merely a week of yearly ritual participation, or do we vicariously take part in events that are extraordinarily remarkable and force us to our knees before the Eternal? Are we making sure that these days fulfill the promise that they have in our lives so that His mind becomes ours?
An Extraordinary Feast
The Days of Unleavened Bread are a memorial to God's law and to His powerful deliverance from Egypt and bondage. Paul explains this significance to the Corinthians and the urgency attached to cease sinning. He says we should not even keep company with a brother involved in flagrant sin! Also, by ridding our homes of sin, we realize that overcoming sin is hard work!
Holy Days: Unleavened Bread
Moses repeatedly reports this vital piece of information: You eat unleavened bread because of what the LORD did.
John W. Ritenbaugh
Sanctification and Holiness (Part 1)
Other Forerunner Commentary entries containing Exodus 13:9: