Q. We recently learned in the daf that the intention for doing a mitzva deuraisa (Biblical) is essential in the compliance of the mitzva. Since during the day we do many mitzvos such as learning Torah or helping others, should one at the beginning of the day declare that all mitzvos one will do, will be with that intention? Since we rule that “kol haosse al daas rishona hu ose” (one who performs does so following the initial intention), the kavana should apply at least for that day.
A. Addressing a similar question (363) we answered: “Horav Shlomo Miller Shlit’a pointed out that in regards to Kavanah in Mitzvos, there is a difference between the commandments Ben Adam Lamakom, or the ones that involve only complying with the will of Hashem and the ones that additionally benefit others or society too. On the former you need intention, on the latter, it is generally accepted that after the fact you comply with the Mitzvah even if performed without intention, as the benefit was done nonetheless.
The following Poiskim maintain a similar view; Ahavas Tzion , drush 10 in the name of his father the Noda B’eyehuda, Yabia Haomer Y.D. 6: 29, also Chida in Pesach Einaim in regards to Tzedakah and Ridbaz 3: 441. However, Bais Halevy drush1, disagrees in regards to Tzdakah and Binas Simcha p. 144 compiled an extensive list of Mitzvos Ben Adam Lechavero that he considers require Kavanah. (See similar in Ahavas Chesed 2: 23: 2).
It is also important to note that the mindful intention has to be close to the fulfillment of the Mitzvah, as Mishna Berurah (60: 7) writes: “To intent before he begins”. Piskey Teshuvos (ibid. 5) mentions that the amount of time before should not be longer than the span of Hesech Hadaas, or time enough for the mind to dwell on something else. (Once you begin doing the Mitzvah with proper intention you fulfill the obligation even if you were latter Masiach Daas, see Minchas Shlomo 1:1).
Therefore a declaration of intention at the beginning of the day may not result in great benefit. However, Horav Shlomo Miller Shlit’a suggests that it may serve as a reminder to later have proper Kavanah, as we carry on with the daily Mitzvos.”
We should mention. that the Baal Hatanya in his siddur indeed mentions to say once a day Leashem Yichud before Boruch Sheomar and following Divrei Pinchas (2) and Shaarei Halocho Uminchag (1: 61), it is effective for all tefilos and mitzvos.
As mentioned above, the Rov maintains that it is worthwhile for one at the beginning of the day to declare that all mitzvos one will do, will be with the intention leshem mitzvah.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a