C. It is the custom of the rabbis to deliver a sermon before the congregation on the Great Sabbath. The main purpose is to instruct the people in the ways of the Lord, to teach them the practices they should perform, namely the laws of cleaning, removing leaven, baking matzah, and other Passover laws.

D. On the Great Sabbath, it is customary to recite the Haggadah from "We were slaves" to "to atone for all our sins." However, the Vilna Gaon did not follow this custom, and his reasoning is because it is stated in the Haggadah, "One might think from the outset, etc."

It appears that there is no definitive decision on how to act practically. It seems that each person should adhere to the custom of their ancestors, as it is implied by the Rema that this matter depends on custom. Consequently, if this custom is not established among them, one should not follow it either, in order to fulfill the opinion of the Vilna Gaon that it should not be said. In this way, one fulfills the obligation of all opinions.