Q. I have been doing Tzom Dibbur (a fast or a day of restriction on speaking) on Yom Kippur for several years. This year, I decided to do a Tzom Dibbur for part of the day every day, and I have some questions:
1). May I do a Tzom Dibur every day for just a couple of hours a day?
A. Mishna Berura (571: 2) quotes that when one desires to accept a day of fasting for redemption or Teshuva, it is better to take on a Taanis Dibbur and abstain from talking anything besides Tefilah and Torah. He adds that from this type of fasting one does not risk any health issues and bodily weaknesses.
He also mentions the letter of the Gaon of Vilna, namely: “Until the day one passes from this world, one should deprive himself, but not necessarily from food or other basic necessities, but by controlling one's mouth and desires, which is actually the foundation of Teshuvah. This is more powerful than any fasting and self-imposed suffering, and every moment that a person closes his mouth, he merits the ‘hidden light’ that no angel or living being can even imagine.”
Horav Shlomo Miller's Shlit'a opinion is that one can accept a Taanis Dibbur even for a few hours a day and it carries the equivalent benefit given to them.
One has to be careful to say "Beli Nedder" or no promises, oaths or wows are being taken before any such acceptance.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a