It was customary in Halab (Aleppo, Syria) to recite a series of verses on Yom Tob before the recitation of the special Psalm for the holiday. These verses are:
"Hashem Be’siyon Gadol Ve’ram Hu Al Kol Ha’amim"
"Ki Yashar Debar Hashem Ve’chol Ma’asehu Be’emuna"
"Bi’dbar Hashem Shamayim Na’asu U’b’ru’ah Piv Kol Seba’am"
"U’lshoni Tehge Sidkecha Kol Ha’yom Tehilatecha"
This custom is mentioned in the work Bet Ha’behira (p. 81).
There were communities that had the practice of reciting these verses three times, but our practice is to recite them only once.
It is also customary during Arbit on Yom Tob to recite before the Kadish before Amida the verse, "Eleh Mo’adeh Hashem Mikra’eh Kodesh Asher Tikre’u Otam Be’mo’adam." Some Mahzorim add also the verse, "Va’yedaber Moshe Et Mo’adeh Hashem El Beneh Yisrael," but the custom in Halab was to recite only the verse "Eleh Mo’adeh Hashem…" The Mahzor Aram Soba actually does not mention the recitation of any Pesukim, but our custom is to recite the verse "Eleh Mo’adeh Hashem…" as is mentioned in several Siddurim.
Furthermore, it was customary in Halab to sing a special song in honor of the Yom Tob at the time when the Sefer Torah is removed from the ark. On the first day of Pesah, they would sing "Emunim"; on the second day, they would sing "Yahid Nora." On the first day of Shabuot, they would sing "Ro’eh Ne’eman," and on the second day, "Bahar Dodi." On Rosh Hashanah, they would sing "Rabat Sab’a," and on Yom Kippur, "Ozreni Kel Hai." On the first day of Sukkot, they would sing "Ma’uzi," and on the second day, "Shir Agid." On Shemini Aseret, they would sing the songs of Simhat Torah. It is a Misva to observe these customs and thereby perpetuate our ancient traditions.