Deuteronomy 29:24-27

All the other nations will ask, “Why has the LORD done this to the land? Why is he so angry?” And the answer will be, “It is because the people broke the Agreement of the LORD, the God of their ancestors, which he made with them when he brought them out of Egypt. They went and served other gods and bowed down to gods they did not even know. The LORD did not allow that, so he became very angry at the land and brought all the curses on it that are written in this book.