Gemara

(R. Chiya bar Ashi): An Asherah may be used for a Lechi.

He would not permit if for a Korah, for Kesusei Michtas Shi'urei (it is as if was already burned and it is less than the Shi'ur).

Sukah 31b (Mishnah): A Lulav of an Asherah (a tree planted for idolatry) or from an Ir ha'Nidachas (a city that must be burned because most of its inhabitants served idolatry) is Pasul.

Question: Rava taught that one may not take a Lulav of idolatry, but if he did he was Yotzei!

Answer: The Mishnah discusses an Asherah of Moshe. Kesusei Michtas Shi'urei.

Support: Presumably, it is like a Lulav from an Ir ha'Nidachas (which cannot be Batel), with which it was taught.

Avodah Zarah 47a - Question (Reish Lakish): If a Nochri bowed to a date tree, may one use a Lulav of the tree for the Mitzvah?

If the tree was initially planted to be worshipped, it is Asur b'Hana'ah, surely one may not use it for the Mitzvah. The question is if the tree was planted and later worshipped.

According to R. Yosi b'Rebbi Yehudah, it is Asur b'Hana'ah, surely one may not use it for the Mitzvah;

He asks according to Chachamim. Is it repulsive to use it for a Mitzvah, or not?

(Rav Dimi): He asks about an Asherah after Bitul. Does Dichuy apply to Mitzvos? (If something became Pasul for a Mitzvah, after the Pesul goes away, may it be used for the Mitzvah?)

Question: Why didn't he settle the question from a Mishnah?

(Mishnah): If one did Kisuy ha'Dam and it became exposed, he need not cover it again. If the wind [blew dirt and] covered it, he must cover it.

(Rabah bar bar Chanah): This is only if it became uncovered. If not, he is exempt.

Question: Even if it becomes uncovered, once the Mitzvah was lost, it should not return!

Answer (Rav Papa): This teaches that Ein Dichuy b'Mitzvos.

Answer: Reish Lakish knew that Ein Dichuy b'Mitzvos. He was unsure if the Tana was certain about this [and says Ein Dichuy even to be lenient], or if he was in doubt [and is stringent to require Kisuy in case the Halachah is that Ein Dichuy].

Reish Lakish's question is not resolved.

Rishonim

The Rif and Rosh (Sukah 14a and 3:1) bring the Mishnah.

Ran (DH Shel Asherah): The Gemara establishes the Mishnah to discuss an Asherah of Moshe, i.e. one that Benei Yisrael found when they entered Eretz Yisrael. Since it belongs to Yisrael, it cannot be Batel, so Kesusei Michtas Shi'urei. If it was a Nochri's, one may not take it, but if he did he was Yotzei.

Rambam (Hilchos Lulav 8:1): If one of the four Minim was from an Ir ha'Nidachas or from an Asherah that was worshipped, it is Pasul. This is even if the Asherah is Batel from being worshipped. If it was of idolatry, one may not take it, but if he did he was Yotzei.

Question: The Rambam disqualifies an Asherah, but says that one is Yotzei with idolatry. He does not distinguish whether they are of a Nochri or a Yisrael!

Answer #1 (Magid Mishnah): Some texts disqualify due to Mitzvah ha'Ba b'Aveirah. This was the Rambam's text. He explains that 'Asherah of Moshe' refers to one that Moshe (the Torah) commanded to destroy, i.e. a tree planted for idolatry.

Objection (Kesef Mishneh): We do not find such a text. Also, R. Yochanan disqualifies a stolen Lulav due to Mitzvah ha'Ba b'Aveirah, but R. Yitzchak bar Nachmani does not (30a). Likewise, R. Yitzchak would not disqualify an Asherah due to Mitzvah ha'Ba b'Aveirah. The Rambam rules like R. Yitzchak! Also, it is unreasonable to be more stringent about idolatry before Bitul, and even if it is of a Yisrael, than an Asherah after Bitul! The Gemara in Chulin disqualifies a Shofar of idolatry even b'Di'eved. How can the Rambam establish this? What is the source to disqualify an Asherah after Bitul?

Defense (Lechem Mishneh Hilchos Shofar 1:3): The Magid Mishnah explains that Mitzvah ha'Ba b'Aveirah disqualifies only when the tree was planted for idolatry. This does not apply to a Shofar. The Gemara disqualified a Shofar due to Kesusei Michtas Shi'urei, i.e. before Bitul. It could not say so regarding Lulav, for cutting it off the tree is Bitul.

Note: If a Yisrael cut it off the tree this is not Bitul (Avodah Zarah 42a). Rav Dimi (47a) taught that Reish Lakish asked about a Lulav from an Asherah after Bitul. Apparently, one might have thought that it is before Bitul!

Answer #2 (Kesef Mishneh): The Rambam holds that one is not Yotzei with a Lulav or Shofar of idolatry before Bitul because Kesusei Michtas Shi'urei. After Bitul it is forbidden l'Chatchilah because it is despised, but b'Di'eved one is Yotzei. If a tree was initially planted to be worshipped, its Lulav is Pasul even after Bitul. This is like it says in Avodah Zarah (47a), that such a tree is forbidden even to people. The Gemara in Sukah explains that the Mishnah discusses an Asherah of Moshe, i.e. it was initially planted to be worshipped. From its inception Kesusei Michtas Shi'urei, therefore even after Bitul it is despised. It is like Ir ha'Nidachas in this sense, that Bitul is not Machshir it for the Mitzvah.

Answer #3 (Lechem Mishneh, ibid.): Rava says that one is Yotzei if the tree was planted and later worshipped. Reish Lakish was unsure about a tree initially planted for idolatry. The Rambam is stringent to say that there is Dichuy; so even after Bitul one is not Yotzei. He holds like Tosfos (Avodah Zarah 47a DH Asherah) that we cannot learn from a Hadas with too many berries (33b). There one can fix it. One cannot force a Nochri to be Mevatel idolatry. One is Yotzei only if it was never forbidden, e.g. a tree that was planted and later worshipped, or a Shofar from a cow to which one bowed, for Ba'alei Chayim are not forbidden.

Answer #4 (R. Mano'ach): Since we must burn an Asherah ("va'Ashereihem Tisrefun ba'Esh"), wherever it is, it is considered burned. Bitul cannot help, just like idolatry of a Yisrael cannot be Batel.

Note: R. Mano'ach's words connote that Bitul does not help for any Asherah, even of a Nochri. However, the Gemara answers that our Mishnah discusses specifically an Asherah of Moshe. Perhaps R. Mano'ach explains this [like the Magid Mishnah] to mean a tree planted to be worshipped.

Rashi (80b DH Aval): R. Chiya would not permit a Korah, for it must be a Tefach wide and strong enough to hold a half-brick. Since an Asherah must be burned, it is as if it was burned, so it lacks the required Shi'ur.

Poskim

Shulchan Aruch (OC 649:3): If one of the four Minim was from an Ir ha'Nidachas or from an Asherah of a Yisrael it is Pasul.

Mishnah Berurah (19): If it was planted and later worshipped, what grew before it was worshipped is permitted to people and forbidden l'Chatchilah for Mitzvos, for it is despised. What grew afterwards is Asur b'Hana'ah and Pasul for the Mitzvah even on Yom Tov Sheni.

Shulchan Aruch (ibid.): If it was of idolatry one may not take it, but if he took it on Yom Tov Sheni he was Yotzei, for we do not require "Lachem".

Mishnah Berurah (21,22): L'Chatchilah, it is forbidden even after Bitul, for it is despised. B'Di'eved one was Yotzei even if it was before Bitul, for it is not destined to be burned, and Mitzvos Lav Leihanos Nitnu.

Rema: This is only if the Yisrael did not intend to acquire it. If he intended to acquire it, it is idolatry of a Yisrael and he is not Yotzei. If the Nochri was Mevatel it before the Yisrael took it, even if the Yisrael acquired it he was Yotzei b'Di'eved.

Gra (DH Yotzei): According to this, we must say that Reish Lakish's question (Avodah Zarah 47a) was whether or not one may use it l'Chatchilah.