Verse 9 and Verse 19 are interesting verses for a man with so many wives. I wonder if he has names in mind as he writes these verses. In one sense he may have created tension in his home by marrying women who did not share his faith. We know that there were times where he made compromises for the sake of his wives that drew his heart away from God. In the big picture though I think we should be reminded that we want to live in such a way that our spouse can find peace at home. This doesn't mean we will be completely conflict free. There may be seasons of difficulty. But it is a reminder that the principles of love your neighbor as yourself applies to our spouses as well. In fact, we would be wise to say this applies to an even greater degree at home.
Verse 30 is great reminder of the sovereignty of God. No plans of this world can thwart His plans. No person can advise you on how to outwit God somehow. Sometimes we consider God's patience with people in their foolishness as man's victory, but that must not be how we view things. God's will shall be done. The best thing we can do is to align our lives with God's plans and purposes. His desires are actually the best things for us as well because He is a loving Father and wants what is best for His children. Our best approach to life must include time in prayer and in Bible study to be clear that we are sticking to the right paths according to the wisdom of God rather than the cleverness and desires of this world.