He heeded their prayer, because they put their trust in Him. 1 Chr 5:20
It is true that the Scriptures teach that obedience motivates God. But it is just as true that trust, or faith, motivates God! In fact, there are many seeming opposites in the Word of God, of which this is one: trust and obedience; in the New Testament, this dynamic commonly is referred to as faith (trust) vs. works (obedience). Another is grace and Law; another is the Word and the Spirit. Mercy and judgment.
To the unrenewed mind, these seem like opposites. It is as if, to human thinking, trust precludes obedience. Grace precludes law. The Word precludes the Spirit. Mercy precludes judgment. Throughout history, man has staked his banner in one camp or the other, and made denominations based on one or the other. The Baptists are famous for their diligent study of the Word, but they have denied the Spirit. The Catholics are famous for their emphasis on works to the near exclusion of faith.
The truth is, the seeming opposites are more like the two sides of a single coin. They seem like they exclude each other, but they do not. Together, they form a unity. Think about this: it takes an enormous amount of trust in God in order to obey God. As an example, consider the command to rest on the Sabbath. When God was teaching this command to Israel, He told them to gather enough manna at the beginning of each day, for their needs for that day, for six days. They had to trust God, that new manna would be there the next day. When someone gathered more, in order to have a store laid aside for the next day (when someone disobeyed God because they did not trust God), the manna bred worms and stank. However, on the sixth day, Israel was to gather enough manna for two days, and not go out and gather on the seventh day, because the seventh day was a Sabbath of rest (Exo 16). God was teaching Israel, to trust Him, first of all, and their obedience flowed out of their trust.
Or the idea that if grace, then not Law. The Law is in fact a gift of grace! Out of our own human wisdom, we do not know what way to walk that will provide for our blessing and prosperity. So God revealed to us His way in the Law, in the form of commandments, so that by walking in it we could be gifted with blessing and prosperity – everything, in fact, that provides for human happiness! Consider that the Law of the Sabbath is a gift of grace, for rest from labor and painful toil, which we earned for ourselves because of our sin (Gen 3:16-19), is a gift of grace!
So it is human nature to say, if trust, then not obedience. If grace, then not Law (or if Law, then not grace, as most Christians today have been trained to think). If Spirit, then not Word. That is man’s way of thinking. God clearly teaches trust and obedience, grace and Law, Spirit and Word, mercy and judgment. When sin has grown too great, judgment becomes an act of mercy.
Now, please note that Scripture once again shines a spotlight on two tribes:
… yet Judah prevailed over his brothers, and from him came a ruler, although the birthright was Joseph’s — 1 Chr 5:2
The reference of a ruler coming from Judah is Messianic, and we remember that the sons of Joseph, Ephraim and Manasseh, were elevated to full tribes within Israel (in this way Joseph received a double portion of the inheritance from his father), and the birthright was given to Ephraim (Gen 48). From Genesis, Scripture has been shining a spotlight on Judah and Joseph, and continues to do so; and we will continue to note it, and trust that Scripture will also reveal its purpose in doing so.