“delight to know my ways.” This is irony. It is obvious from the context that the people sought God to get what they wanted, not sought Him to know and obey His ways. This is one of the many places where totally selfish people seek God to get things from Him without giving a thought about whether they themselves are obeying God.
“a nation.” God usually refers to Israel as His people or the people. But here he refers to them as a nation, a word that He regularly uses for the pagan nations. Thus there is buried in the vocabulary God’s assessment of Israel: they were acting like pagans.
“did righteousness.” That is, did righteous things. (See commentary on Matthew 5:6).