For some reason this didn’t post. So:

Please forgive my slackness; it appears I haven’t put any memory work up for a few weeks. I’ll try and get us caught up on the chronological study and then get back on our basic toolbox and the Sermon on the Mount Series.
Numbers posed a little difficulty in choosing a single verse that encapsulates the entire book, but I think Moses lands on an issue that transcends all of scripture in chapter 32.

“But if you will not do so, behold, you have sinned against the Lord, and be sure your sin will find you out.” Nu 32:23

Now in context (very brief in context) the nation of Israel is crossing over the Jordon to potentially possess the “promised land”. The Scriptures say that the tribes of Reuben and Gad had “very great number of livestock” (32:1) so they were desiring to stay in the land before crossing the Jordon as this would accommodate their herds. Their request to Moses brought concern because the Israelites had not yet conquered the “promised land” and Moses thought perhaps they were trying to get out of helping their brothers in the coming battles. Once the tribes had come to an agreement this was not the motive Moses was quick to remind them of the promises ramifications. Should this not be their motive they have sinned ultimately against the Lord…and your sin will find you out.

The significance of this issue transcends all of Scripture as I was reminded this morning in my reading. Jesus reminds us (Mt 15:10-20) that our sin ultimately comes from the depths of us, we are actually defiled from within our heart. Solomon also wrote in Proverbs, “For as he thinks within himself, so he is.” (Pr 23:7) This issue is why Jesus could declare dogmatically in the Sermon on the Mount that it really didn’t matter that you had physically murdered anybody if your angry with them from the heart you might as well have murdered them. It wasn’t the issue if you’ve physically committed adultery with a woman, if you have looked at her with lustful intent; you’ve committed adultery already with her IN YOUR HEART.
My point or more importantly God’s point is that everything is evaluated at a heart level and we must be consistently exposing our hearts to God’s Word (Heb 4:12) to have the thoughts and intents of our hearts evaluated by God’s Word. The tribes of Reuben and Gad were called to account and we as followers of Jesus Christ (and I never assume that, only for the sake of the discussion) must be constantly examining ourselves (2Cor 13:5) in light of the Scriptures.