Rabbi Menachem Mendel Lefin is known mostly for his book Cheshbon HaNefesh. While researching biographical notes about him, I came across the following sentence on Wikipedia:
He campaigned in favor of adding general education to the standard curriculum in Jewish schools, and he was a fierce opponent of the Hasidic movement and the Kabbalah, which he viewed as "nonsense."
You can find the quote here: https://en.wikipedia.org/wiki/Menachem_Mendel_Lefin
Whoever wrote that line did not provide a source and so I'm asking if anyone knows of a source to back up the idea that Rabbi Lefin "was a fierce opponent of the Hasidic movement and the Kabbalah, which he viewed as "nonsense."