Day 9, 10, 11 & 12's scriptures actually go together so I am going to do the whole passage first:
Ephesians 5: 4-11
4 Obscene stories, foolish talk, and coarse jokes—these are not for you. Instead, let there be thankfulness to God.
5 You can be sure that no immoral, impure, or greedy person will inherit the Kingdom of Christ and of God. For a greedy person is an idolater, worshiping the things of this world.
6 Don’t be fooled by those who try to excuse these sins, for the anger of God will fall on all who disobey him.
7 Don’t participate in the things these people do.
8 For once you were full of darkness, but now you have light from the Lord. So live as people of light!
9 For this light within you produces only what is good and right and true.
10 Carefully determine what pleases the Lord.
11 Take no part in the worthless deeds of evil and darkness; instead, expose them.
Sometimes, after reading a passage, I like to put it in the message translation. The Message, is not really a translation but it is a summerization of the scripture in today's language. I thought this one was really good. Thanks bible.com
Ephesians 5: 4-11
3 -4Don't allow love to turn into lust, setting off a downhill slide into sexual promiscuity, filthy practices, or bullying greed. Though some tongues just love the taste of gossip, those who follow Jesus have better uses for language than that. Don't talk dirty or silly. That kind of talk doesn't fit our style. Thanksgiving is our dialect.
5You can be sure that using people or religion or things just for what you can get out of them—the usual variations on idolatry—will get you nowhere, and certainly nowhere near the kingdom of Christ, the kingdom of God.
6 -7Don't let yourselves get taken in by religious smooth talk. God gets furious with people who are full of religious sales talk but want nothing to do with him. Don't even hang around people like that.
8 -10You groped your way through that murk once, but no longer. You're out in the open now. The bright light of Christ makes your way plain. So no more stumbling around. Get on with it! The good, the right, the true—these are the actions appropriate for daylight hours. Figure out what will please Christ, and then do it.11 -16Don't waste your time on useless work, mere busywork, the barren pursuits of darkness. Expose these things for the sham they are. It's a scandal when people waste their lives on things they must do in the darkness where no one will see. Rip the cover off those frauds and see how attractive they look in the light of Christ.
As children of God, we need to be aware of everything around us and surround ourselves with people that are walking the same path we are. We were once in darkness 'walking through murk' but now we are in the light and we should walk in that light proudly, abstaining and removing ourselves from situations and people that do not nurture our new walks.