That shameful thing - i. e., Baal; public establishment of idolatry, such as actually took place in the reign of Manasseh (2 Chronicles 33:3. Contrast 2 Kings 18:4).
Matthew Henry
Concise Bible Commentary
Evil pursues sinners, and entangles them in snares, out of which they cannot free themselves. Now, in their distress, their many gods and many altars stand them in no stead. And those whose own prayers will not be heard, cannot expect benefit from the prayers of others. Their profession of religion shall prove of no use. When trouble came upon them, they made this their confidence, but God has rejected it. His altar shall yield them no satisfaction. The remembrance of God's former favours to them shall be no comfort under troubles; and his remembrance of them shall be no argument for their relief. Every sin against the Lord is a sin against ourselves, and so it will be found sooner or later.
SDA Bible Commentary (limited)
Volume 1-7
13. Number of thy cities. For comment see on ch.2:28.
Shameful thing. Literally, “the shame,” shown in the succeeding clause to refer to the image of Baal (see on ch.2:26). On the revival of Baal worship by Manasseh, son and successor of Hezekiah, see 2 Chron. 33:1-3.