The Pesukeh De'zimra section of our morning prayer service begins with a special introductory Beracha – Baruch She'amar. Some say that this is the Beracha over the Misva of Pesukeh De'zimra. Therefore, if, for whatever reason, one who neglected to recite Baruch She'amar before Pesukeh De'zimra does not recite it afterward. Interestingly enough, this blessing does not appear anywhere in the Talmud. The Or Zarua (Rav Yishak of Vienna, 13 th century) writes that the Ansheh Kenesset Ha'gedola (Men of the Great Assembly), which existed in the beginning of the Second Commonwealth, instituted the recitation of this Beracha after the text descended from the heavens. A piece of paper bearing the text of Baruch She'amar fell from the skies, and so the Rabbis of the time chose to incorporate it into the daily prayer service. An allusion to this recitation can be found in a verse in Shir Hashirim (5:11): "Rosho Ketem Paz" – "His head is the finest of gold." The word "Paz" in Gematria equals 87 – the number of words in Baruch She'amar, and thus hints to the fact that "Rosho" – the beginning of the prayer service, features "Ketem Paz" – the beautiful, "golden" blessing of Baruch She'amar. Due to the unique importance of Baruch She'amar, it was instituted to be recited while standing, just as the angels stand while praising G-d in the heavens. The Peri Hadash (Rav Hizkiya Da Silva, 1659-1698) raised the question of how we are allowed to recite this blessing, given that it was not mentioned in the Talmud. Seemingly, we do not have the authority to introduce new Berachot which the Gemara does not instruct us to recite. In truth, however, the Tur (Rabbenu Yaakob Ben Asher, 1270-1340) brings a source tracing the origins of this blessing back to the times of Rabbi Yishmael, who lived during the Second Temple era. And the Hida (Rav Haim Yosef David Azulai, 1724-1806) notes that this blessing is mentioned in the Zohar, which is attributed to Rabbi Shimon Bar Yohai, one of the Tannaim. Therefore, it certainly has a legitimate basis, and there is no room to question the legitimacy of reciting it. The Mishna Berura (Rav Yisrael Meir Kagan, 1839-1933) writes that since this Beracha is not mentioned in the Talmud, it may be treated more leniently than other Berachot. Therefore, if somebody hears somebody recite a different Beracha while he recites Baruch She'amar, he may interrupt his recitation of Baruch She'amar to answer "Amen" to that other Beracha. However, Halacha does not follow this opinion. We treat Baruch She'amar no differently than other Berachot, and thus one may not interrupt his recitation of Baruch She'amar to answer "Amen" to another Beracha. Summary: Baruch She'amar is regarded as the introductory blessing to Pesukeh De'zimra, and therefore one who neglected to recite it before Baruch She'amar does not recite it afterward. As with all Berachot, one who hears a different Beracha while reciting Baruch She'amar does not interrupt his recitation to answer "Amen" to that other Beracha. Due to its unique importance, Baruch She'amar is to be recited standing.