I believe it was Rav SZA who wrote/said that there are three "threes" (3 things that people do having to do with "3") that are made up.
Does anyone know where this is written and/or what they are?
Reb Shlomo Zalman in Halichos Shlomo Hilchos Pesach Perek 13 Footnote 11 says;
There are 3 things that people say you need to do 3 times, however there is no mekor to any of them:
- A child needs to fast 3 times before their Bar/Bas Mitzvah
- A Sefer Torah must be read 3 times in a Bais Avel
- A person needs to wash 3 times each hand before davening