from TorahJews.org
It happened in the fledgling Slabodka Yeshiva in Bnei Brak. The war was still raging in Europe the angel of death had almost full reign in the killing fields of Europe. As Lithuania was being decimated Rabbi Isaac Sher resolved to rebuild from scratch in the Holy Land, and founded the Slabodka Yeshiva in Bnei Brak. Thus a rejuvenation was beginning in the land of Israel.
Rabbi Sher asked to small group of students if eventually they would want to return with him to Slabodka in Lithuania after the war. One student replied, “Absolutely not! I should go back and leave behind the Holy Land?”
But Rabbi Sher countered, “We will accomplish much more there. We will be able to learn and grow more over there.”
One of Rabbi Sher’s early students was Rabbi Shlomo Hoffman. He witnessed this exchange and recalled:
We students living in the Holy Land were not swayed. We could not contemplate how the Rosh Yeshiva could even think of going back there and leaving the Holy Land! Rabbi Sher then told us, “I see that you have been drugged by Zionism.”
I remember asking Rav Isaac, “But how could I be drugged by Zionism? I have not even read one Zionist book. I have been within the four walls of the Yeshiva and nowhere else.”
Rav Isaac replied, “Just like mushrooms grow from the moisture in the air, a person is influenced by the sentiments in the air. If I am telling you that you will accomplish much more in Lithuania and you still insist on staying here, that means you have been drugged by Zionism. The air is permeated with Zionism and it has an influence on you, even unknowingly.” (Yated Neeman, Sep 23, 2022)
https://torahjews.org/rabbi-yitzchok-isaac-sher-rosh-yeshiva-of-slobodka-1875-1952/