The Yahrzeit of the Bas Ayin (Rebbe Avraham Dov ben Rebbe Dovid zy'a) Chazal say (Chulin 7:) "Tzaddikim are greater after their passing than when they were alive." This is particularly so on their yahrtzeit because that is when their holy ruach (spirit) hovers and rests on their grave to bring salvations to those who daven there and seek Hashem's compassion. The Yismach Yisrael (Me'oron shel Yisrael 14 Shevat 2) says that a yahrtzeit is called הלולא because, in Aramaic, a chasunah is also called hilulah. The celebration of a yahrtzeit is compared to the joy of a chasunah. And just like at a chasunah, the kesubah is read before the chosson to remind him of his obligations to the kallah, so too, on the day of the hilulah of a tzaddik, the tzaddik is reminded of his obligations to the people who are בצלו החוסים reside under his shade (which means those who are students of this great tzaddik). And this doesn't only mean...
