What did Hezekiah say that their ancestors did in the sight of Yahweh?

Hezekiah said that their ancestors trespassed and did what was evil in the sight of Yahweh their God. [29:6]

What did their ancestors not do in the place where Yahweh lived?

Their ancestors did not burn incense or offer burnt offerings in the holy place to the God of Israel. [29:6; 29:7]