One of the chapters of Tehillim that we add before Baruch She'amar on Shabbat morning is the 90 th chapter – "Tefila Le'Moshe," which concludes with the famous verse, "Vi'yhi Noam Hashem Elokenu Alenu U'ma'aseh Yadenu Konena Alenu U'ma'aseh Yadenu Konenehu" – " May the pleasantness of Hashem our God be upon us; may He establish the work of our hands for us — establish the work of our hands." The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in Parashat Vayigash, discusses the special significance of this verse. He interprets this prayer as a request that G-d should accept our Misva observance despite the fact that we do not perform them with all their deep intentions. We confess that we do not recite our prayers and perform our Misvot in the manner that we ideally should, with full concentration and with a keen understanding of their deep meaning and significance, but we ask that Hashem should nevertheless accept our service. The Rashash (Rav Shalom Sharabi, Yemen-Jerusalem, 1720-1777) explained this verse differently, noting that every Misva we perform brings a special spiritual light, but every misdeed we commit has the effect of extinguishing that light. When we recite this verse, we ask Hashem to restore the light of our Misvot, to forgive us for our wrongdoing so that our good deeds can once again shine with all their brightness. The Ben Ish Hai notes that some have the practice of reciting this verse twice before performing a Misva, and he explains that this is done to satisfy both meanings. It is recited first to ask that Hashem accept our Misva despite our failure to have all the lofty intentions, and a second time as a prayer that our Misva shall shine brightly despite our sins. Rav Meir Mazuz (1945-2025), in Ish Masliah, explains that some recite this verse twice because its recitation itself constitutes an important Misva, such that it must be recited first as a preparation for its recitation. The Ben Ish Hai implies that this verse should be recited a second time not only before performing a Misva, but also when this chapter of Tehillim is being recited, such as on Shabbat morning. Common practice, however, clearly does not follow this opinion. Many of those who recite "Vi'yhi Noam" before performing a Misva do so at the conclusion of the "Le'shem Yihud" declaration made for the purpose of preparing for the Misva act. Among Syrian Jews, the custom in Damascus was to recite the "Le'shem Yihud," whereas the practice in Aleppo was not to recite 'Le'shem Yihud," and to recite only "Vi'yhi Noam."