One of the more interesting pioneers of the haskalah movement was R. Shelomo Zalman Hanau (Katz). Hanau's works mainly concern grammar and, in that vein, corrections to the siddur. Hanau's first book, Binyan Shelomo, Frankfort A.M., 1708 was published when he was 21. This book focuses on grammar, but, as we have already discussed, was important in the development of the Siddur. (Additionally, see S.'s recent post on Hanau here.) This book is now up for auction, however, I must note that there seems to be an exaggeration regarding the scarcity of a particular page.
The catalog describes the book as follows:
The author was born in 1687 and was noted for his many books regarding the foundation of the Hebrew language . . . The author corresponded with many Torah luminaries regarding his subject of expertise. His first book, Binyan Shlomo . . . [a]s a young scholar he spoke sharply against many sages who preceded him by hundreds of years. As the years passed, the author regretted his sharp language and printed a unique apology in which he notes the names of the sages whom he did not properly honor. This list features at least five leading Torah scholars from previous generations. To the best of our knowledge, this leaf is not extant today and is not listed in the C.D. of the Bibliographic Project. The book itself was never reprinted and is very rare today. To the best of our knowledge, this is the only known copy with the apology leaf.
Judaica Jerusalem, Elul 2009, lot # 144, (emphasis in original). There are a number of corrections in order. First, the description states that there was only one edition of Binyan Shelomo "and it was never reprinted." That is incorrect. Aside from two photo-reproductions done by Copy Corner and Guttman, Binyan Shelomo was reprinted in 1723. Vinograd, in his bibliography, Otzar Sefer ha-Ivri, lists this book as extant the Annenberg Library, which, according to their online catalog, the book can still be found. Turning now to the "apology leaf." It is correct that the leaf is rare, however, it is an overstatement to say this is the only known copy with the leaf. Indeed, the existence of the leaf is not mentioned in Vingrad's Otzar ha-Sefer ha-Ivri, Jersusalem: 1994, vol. II, Frankfort A.M. # 218. But, the leaf was mentioned already in 1865 and the fact that Hanau issued an apology was mentioned as early as 1715. The first mention that Hanau issued an apology (although there is no mention of a special leaf) was in Johann Christoph Wolf's Bibliotheca Hebraea, Hamburg: 1715. (S. has kindly translated the relevant passage here.) Shadal in Prolegomenon, Grimmae: 1838, 61-2 n.1, also records Wolf's comments. (See S.'s comments regarding the use of Prolegomenon here.) The first to republish the apology leaf was Meir Wiener in Ha-Maggid, May 17, 1865, Ha-Tozfeh le-Maggid. Wiener decided to republish the text of the entire leaf "due to its rarity." Wiener obtained a copy from the Rosenthal library and in the catalog for the library by Roest, Yodeah Sefer, he says "that in my copy I have an extra page at the end." Yodeah Sefer, letter Bet, # 304. This notation was then recorded in Wiener's bibliography of St. Petersberg library, Kohelet Moshe. Wiener says "that the extra page at the end, which Roest records and where the author asks for forgiveness for insulting various authors, is not in this copy." While it wasn't in these copies, nor is it in the copy on Hebrewbooks.org, it is in the JNUL's copy which is online here. Additionally, we have a copy which has this leaf, making it at least two others in existence.
We now turn to what precipitated the inclusion of this leaf. According to the auction description, R. Hanau did this on his when "the years passed" and he "regretted his sharp language." According to Roest, however, "it is without a doubt that Hanau was forced by the Rabbis to print this apology, just like R. Moshe Hayyim Luzzato." Roest, op cit. Thus, according to Roest, the apology was not brought about from Hanau's own introspection but because of the Rabbis. Indeed, Friedberg in Bet Eked, says "that the author [Hanau] was forced by the Rabbi of Frankfort A.M. and his bet din to print a special page, in a smaller format, which was appended to the work, in which the author asks for forgiveness from the authors which [Hanau] insulted in his book." Bet Eked, letter Bet, # 1238. Similarly, Wolf states "Rabbis of Frankfurt were going to destroy it by flames" had Hanau not agreed to print the apology. So according to these sources, Hanau was forced to print this apology. According to a contemporary source, we can place the retraction before 1713. This is so, because in Siddur of R. Azriel and R. Eliah of Vilna, published in 1713, they note that Hanau printed a page "asking for forgiveness." Additionally, according to this source, the request for forgiveness was at the behest of the Frankfort bet din. R. Azriel and R. Eliah say that the page was printed "due to the decree of the head and leaders of the holy city Frankfort A.M." R. Azriel and R. Eliahu then continue, and mention the possibility that R. Hanau deserved to be placed under the ban due to his disrespectful words. David Yitzhaki appears to have misunderstood R. Azriel and R. Eliah's words as Yitzhaki says "that Hanau was almost placed under a ban." D. Yitzhaki, "The Editors of the Ashkenzi Siddur & R. Shelomo Zalman Hanau and his Forgeries," in Luach Eres, Toronto, 2001, 32. If, as it appears, Yitzhaki's source is the quote from R. Azriel and R. Eliah, that quote merely says that it was R. Azriel and R. Eliah's opinions that Hanau "should" have been placed under the ban, they never say that there was a serious consideration of actually placing Hanau under a ban. Of course, according to Wolf's version, Binyan Shelomo was to be consigned to the flames, also implying a ban. Wolf, however, provides no source for this assertion, and it seems unlikely that R. Azriel and R. Eliah would fail to mention the fact that Binyan Shelomo was almost destroyed.
There is one more version of the story behind the retraction that is worth noting because it contains a major error. This is a real honker.* Moshe Carmilly-Weinberger, in Sefer ve-Seif, apparently confused R. Hanau's Binyan Shelomo with another book that has the same title. Carmilly-Weinberger writes (172-73):
R. Yehezkel Landau the Noda be-Yehuda, stood with R. Yisrael Lifschitz [regarding the controversy surrounding the infamous Get of Cleves], who was in conflict with the head of the Frankfort bet din, R. Nathan Maz and R. Shelomoh Hena [sic] the author of the Binyan Shelomo. Since R. Landau agreed with R. Yisrael Lifschitz, the enemy of R. Shelomoh Hena, [Hena] banned the work of the Noda be-Yehuda.
Carmilly then quotes a passage from the Hida's work Shem ha-Gedolim in support of the above statement:
And because of this [fight about the Get of Cleves], when the book Noda be-Yehuda was published the Goan, author of Binyan Shelomo and his bet din prohibited anyone from reading [the Noda be-Yehuda]. The Noda be-Yehuda, however, took the opposite view and he said I tell anyone who is reasonable to go ahead the Binyan Shelomo, to look and see ערות האר"ש השמנה הוא אם רזה (a word play implying that there isn't much in the Binyan Shelomo).
Carmilly then continues, and he links the extra leaf in the Binyan Shelomo, to these statements explaining that Hana asked forgiveness for all those people he insulted. Carmilly implies that the forgiveness related to the controversy about the Get of Cleves! This is wrong. First, and foremost, the controversy regarding the Get of Cleves occurred in 1766, Hanau died in 1746. Moreover, Hanau could not have counseled people not to read the Noda be-Yehuda as that was published in 1776 some thirty years after Hanau died. Additionally, it is clear that Carmilly never saw this leaf as we will soon see, this leaf requests forgiveness from rishonim and doesn't mention anyone involved in the Get of Cleves controversy.
Carmilly confused two books with the same title, Binyan Shelomo. The first, by Hanau on grammar which is the subject of our discussion, and the second one, is written by R. Nathan Maz, and was published in 1784. R. Nathan Maz  who was involved in the Get of Cleve controversy and who was on the Frankfort bet din (something that Hanau was not), was the subject of the above discussion. What makes this error even more ironic is that Nepi-Ghirondi, in his Tolodot Gedolei Yisrael, correctly notes that R. Maz authored a work titled Binyan Shelomo. Carmilly, however, faults Nepi-Ghirondi "incorrectly associating Binyan Shelomo with R. Maz and, instead, the correct author is R. Hanau!" Id. 172 n.297. Of course, if one looks at the Hida in the original, it is also apparent that he is not referring to Hanau but to a different book with the same title.
Turning to the text of the "request for forgiveness." This text reminds me of a story I heard regarding a relative. According to the story, A. calls C. "stupid." A's mother then tells A. to apologies, to which A. turns to C. and says, "I am sorry you are stupid." Hanau's request for forgiveness is similar as after offering a general request for forgiveness, Hanau then goes ahead and records every objectionable thing he said. For example, Hanau says
I erred in my ways when I disagreed with the authors. I was too verbose and, at times, I insulted the authors . . . therefore I come to ask forgiveness: from the prince Don Isaac Abarbanel when I wrote that "he speaks without logic and his words make no sense," and in another place I wrote about him that "this statement [of the Abarbanel] is because of his lack of knowledge and that he didn't understand what was being said" . . . Regarding the Ibn Ezra I wrote "he didn't subject this statement to logic"
While this apology my be tongue in cheek, it seems to have appeased many or, at the very least, many thought Hanau's next book didn't suffer from the same lack of respect. In R. Yehezkel Katzenellenbogen's approbation to Sha'arei Torah, Hamburg 1717, he notes that while Hanau had in his prior work been too harsh with his language in "Sha'arei Torah, [Hanau] speaks with the appropriate measure of respect as I [R. Katzenellenbogen] have carefully checked."
 Wiener, in his article in Ha-Maggid (17 May 1865), questions the existence of this edition. He claims that there is no such edition and that the abbreviation used for the date was misinterpreted.
 It should be noted that R. Azriel and R. Eliah were not dispassionate observers. Part of the reason that Hanau wrote Binyan Shelomo was to disagree with R. Azriel and R. Eliah's opinions regarding proper punctuation of the Siddur. See Jacob J. Schacter, "Introduction," in Luach Eres, op cit., 11-12. R. Azriel and R. Eliah derogatorily refer to Binyan Shelomo as "Hurban Shelomo."
 For more information on R. Maz see M. Horovitz, Rabbanei Frankfort, Jerusalem:1972, 134-43.
 This did not appease everyone. R. J. Emden really disliked R. Hanau's positions. See Jacob J. Schacter, Luach Eres, op cit., 14-25.
* I would like to thank A. Rottenberg for calling this error, as well as numerous other errors in Carmilly-Weinberg's book, to my attention.