"Rav Alexander Ziskind is a great as his Sefer and his sefer is as great as him" so proclaimed the Vilna Gaon about the great and holy Michaber of the classic sefer Yesod V'Shoresh HaAvodah.
In the second half of the 18th century when Chasiddus was just beginning and the sharp reaction to it created a warlike atmosphere between the two camps, Rav Alexander Ziskind was a rare individual that transcended the battle and was beloved by both sides. His classic sefer Yesod V'Shoresh HaAvodah on tefila and Moadim is cherished by both Misnagdim and Chassidim alike and learned by all.
Rav Aharon of Karlin travelled to Horodna to try to bring Rav Alexander Ziskind to Chasiddus. His goal was to persuade him to come to the Maggid of Mezeritch the successor of the Baal Shem Tov for Shabbos. Successful in his mission, Rav Aharon returned to Mezeritch for Shabbos with Rav Alexander Ziskind. During the Friday night seudah the Maggid did not speak any Divrei Torah only Divrei Chol. This caused great pain to Rav Alexander Ziskind but he patiently waited for the morning seudah. The scene replayed itself again with an absence of Divrei Torah and only Divrei Chol. Sitting through Seudah Shlishis with the same results totally destroyed Rav Alexander Ziskind. As soon as Motza'ei Shabbos came he ran out of Mezeritch never to return again. When Rav Aharon of Karlin asked the Maggid why he spoke Divrei chol and not Divrei Torah he replied that he saw in Rav Alexander Ziskind a Tzaddik Tamim and did not want to influence him to change his ways in Avodas Hashem.
Rav Alexander Ziskind was imprisoned for a full year and half for trying to leave Hamburg with money he collected for the poor in Eretz Yisroel. As soon as he was released he immediately began to collect once again. When asked why he would do this he answered that "do you think that because of the danger to me the poor people sitting before Hashem in the Holy Land should starve?"
Before one Pesach a Jew was arrested in a blood libel and sentenced to a cruel death unless he converted. Rav Alexander Ziskind was worried he would lose his resolve and cave in. He obtained special permission to visit this person in jail where he gave him Chizzuk to stand strong and die "Al Kiddush Hashem" despite the torture. On the day the sentence was to be carried out, while all the local Jews were hiding fearing a pogrom, Rav Alexander Ziskind bravely went to the town square among the goyim to watch the murder of the innocent Jew. As the Jew was murdered Rav Alexander Ziskind heard him make the bracha that one makes before dying Al Kiddush Hashem. He then went back to Shul and made and Azkara for the martyred Holy Neshama.
Details about his life are scarce. His place of birth is unknown although he lived in Horodna. He was a talmid of Rav Aryeh Leib Epstein the Baal HaPardes and he never accepted any rabbinical position. He was believed to be under sixty at the time of his death. About his fiery sefer on Kavonas HaTefila he testified on himself that all his own personal tefilos were in accordance with his sefer and he even added many other Kavanos that he did not write in the Sefer.
In his Tzavaah he writes that his name Alexander has a gematria of 365 for the Mitzvos Lo Saaseh and Ziskind with its seven letters equals 248 for the Mitzvos Aseh, "all of which I accepted to keep in any possible way." He did not allow any titles on his Matzeiva except "Here lies Alexander Ziskind... Oveid Hashem Yisborach" He was niftar in 5554/1794. Yehi Zichro Boruch