There is an ancient custom to add to the morning Pesukeh De'zimra service the recitation of "Az Yashir," the jubilant song of praise which Beneh Yisrael sung after the miracle of the splitting of the sea. We begin the recitation two verses earlier, with "Va'yosha Hashem…" (Shemot 14:30). This practice appears already in the Siddur of Ram Amram Gaon (Babylonia, 9 th century), though the Rambam does not include this recitation in his text of the prayer service. Regardless, it has been accepted to recite "Az Yashir," and the Arizal and others revealed the great spiritual benefits of this practice. Some suggested that the daily recitation of "Az Yashir" is included in the song's introductory verse, which tells that Beneh Yisrael sang this song "Le'mor" – literally, "to say." This alludes to the fact that this song was written to be sung not only at the shores of Yam Suf, but also for all generations, each day, and even in the times of Mashiah, when we will continue to sing this song to praise Hashem for the miracles He has performed. So significant is the daily recitation of "Az Yashir" that the Midrash Shoher Tob teaches that one who sings this song with Kavana (concentration) is cleansed from his sins. This is inferred from the Torah's account of Moshe leading Beneh Yisrael away from the shores of the sea after they sung this song – "Va'yasa Moshe Et Yisrael Mi'Yam Suf" (Shemot 15:22), which the Midrash explains to mean that the people were brought away from their sins at the sea. Before the miracle, when Beneh Yisrael found themselves trapped by the Egyptian army, they complained bitterly to G-d. Their joyous singing of "Az Yashir" had the effect of atoning for their inappropriately angry protests. By extension, anyone who reenacts our ancestors' jubilant singing of "Az Yashir" is likewise absolved of his wrongdoing. The work Solet Belula instructs that one should sing "Az Yashir" with the Te'amim – the cantillation notes with which this section is chanted when it is read from the Torah in the synagogue. Indeed, the custom in our Syrian community is that the Hazan chants "Az Yashir" with the Te'amim. On the two occasions when the section of "Az Yashir" is included in the congregational Torah reading – namely, Shabbat Parashat Beshalah (Shabbat Shira) and on Shebi'i Shel Pesach – it is customary for the congregation to chant "Az Yashir" all together during Pesukeh De'zimra, with the Te'amim. Several sources teach that whenever a person finds himself in a challenging situation, where he faces a difficult problem, he should read "Az Yashir" with Kavana. This recitation can help "split the sea" for him, bringing him the salvation he needs just as G-d split the sea for our ancestors to rescue them from the pursuing Egyptians. One should recite "Az Yashir" with genuine feelings of joy. We evoke these feelings by taking a moment to reflect on the miracles that G-d performed for our ancestors and the miracles He performs for us even today, protecting us from harm, providing our needs, and helping us achieve what we set out to do. Some Poskim maintained that the joyous "Az Yashir" song should not be recited in a house of mourning. The widespread practice, however, is to recite it even in a house of mourning. Some have the custom to stand during the recitation of "Az Yashir," but our custom is to recite it while seated.