This verse names the last evil act of King Manasseh, and at the same time it is the transition to the unfolding of the rest of this story. The final evil act is that Manasseh placed a carved image of the goddess Asherah (a Canaanite or Phoenician idol) in the temple. Now, similar actions of Manasseh have already been mentioned in the 2 Kings 21:3–5, but by adding here that an Asherah image was placed in the temple could point to the fact that this was even worse than what happened previously. It could mean that the image was placed in the holy place of the temple or perhaps even in the Most Holy Place of the temple (see 1 Kings 6:16).
2 Kings 21:7 partly repeats what was said in 2 Kings 21:4, but expands on this, as David and Salomon are also mentioned now. Moreover, the citation of what the Lord says is expanded upon. That is why in this verse there is greater pressure than in the previous verses with more or less the same content. As a result, the contradiction of how the Lord intended the temple to be used and what Manasseh had done with it becomes an even more painful contrast.
7 And the carved image of Asherah that he had made he set in the house of which the LORD said to David and to Solomon his son, “In this house, and in Jerusalem, which I have chosen out of all the tribes of Israel, I will put my name forever.