Reply To: Interesting Customs on Pesach

A minhag cannot overrirde a chiyuv d’oraysa. The Gra felt that being strict about gebrots comes at the expense of simchas yom tov.

Chacham Ovadia was fond of saying, ‘He who adds, subtracts.’ With every chumra, you have a loss [from another angle]. Such as those people who follow the shiur of the Chazon Ish for reviis for arba kosos (5.3 oz) but they are unable to drink the whole cup, and really the halacha is that l’chatchila you should drink the whole cup. So their chumra (of using a bigger shiur) results in a kula (they end up being yotzi only b’dieved because l’chatchila you have to drink the whole cup).

Or people who drink to excess on Purim (to be yotzi) and perhaps as a result they miss Maariv and Krias Shema and they are mevatel a mitzvas aseh d’oraysa of krias Shema.

Or people who have a “minhag” not to learn on nittel nacht and it comes at the expense of the chiyuv d’oraysa of talmud torah.