Rabbi Mordechai Leib Winkler, rav of Madd, wrote the following to Rabbi Yonasan Steiff, rav of Budapest, who asked his opinion about an organization to settle Eretz Yisroel, probably a project of Agudah (printed in Levushei Mordechai, v. 3 Yoreh Deah 49):
You are correct in opposing them, for the Zionists will have the power, and who knows what they will decree on a group like this.
And everyone knows what Rabbi Yonasan Eybeshutz writes on the Haftarah of Parshas Vaeschanan, that even if the Jewish people gathers together to go to Eretz Yisroel and the nations of the world agree, we must not go, for it is only a temporary permission. Who knows if they will not change their minds and decree another exile worse than the first one? This, he says, is the meaning of Shir Hashirim 8:4: Why do you arouse and why do you awaken the love before it is desired - until the true time for redemption arrives?
Buying up farmland in Eretz Yisroel is a waste of time and a sickness
And Rabbi Yaakov Emden, in the introduction to his Siddur called Sulam Beis Eil, writes at length about the greatness of the mitzvah to settle in Eretz Yisroel, saying that outside the Holy Land we are under the power of an angel who causes us to forget our Torah learning. He recommends that whoever is wealthy enough to support himself for the rest of his life should go and live in Eretz Yisroel, learning Torah and serving Hashem. But, he says, buying up farmland in Eretz Yisroel is a waste of time and a sickness.
And the Chasam Sofer comments on the Haftarah of Parshas Shoftim: The Jewish people have already deserved many times to be redeemed through an incomplete redemption, or – better yet – there could have been a real redemption as in the time of the Second Temple, but that is not desirable. Even if we ourselves would settle for such a redemption – just to be redeemed – our holy forefathers would not consent now to anything less than a complete redemption, in which we will see Hashem's return to Zion with our own eyes.
However, we must ask: If Jews are discouraged from returning to Eretz Yisroel en masse, why did Chazal (Gittin 8b and Bava Kama 80b, quoted in Orach Chaim 306:12) give special permission to tell a gentile to write on Shabbos in order to purchase a house in Eretz Yisroel? Perhaps the answer is that this law applies only to a house, not to a field or a vineyard. [Chazal wanted Jews to live in Eretz Yisroel during exile only to study Torah, not to farm the land and make a living. This would guarantee that only a select few would come, and there would be no massive takeover of the country.]