R. Abraham David b. Judah Loeb Lavot (1815-1890), noted rabbinical scholar, Chabad disciple, was the Rabbi and Judge in Nikolaev, Russia. Nikolaev, a port on the Black Sea, was traditionally a closed city to Jews, except for those directly involved in port activities. R. Lavot, upon the request of his Rebbe the Zemah Zedek, established a synagogue and eventually a very successful Yeshiva under the guise of "port employees". Among his other works is Kav Naki (Warsaw 1868) on the laws of divorce, it has seen several editions and is utilized by many rabbis to this day.