During the entire month of Nisan we do not say Tachanun¹ or Tzidduk Hadin² (burial service), and we do not say Tzidkasecha on Shabbos at Minchah.³ 429. It is customary⁴ from Rosh Chodesh on, to read (from the Seifer Torah) the parashah of the Nasi⁵. On Rosh Chodesh Nisan the Tabernacle was erected, and in honor of its dedication, during the ensuing twelve days, each Nasi had his day on which he brought a special offering, as is written in Numbers 7:10–7:89. who brought his offering on that day. On the thirteenth day of the month, we read in parashas Beha'alosechah until "Kein asah es hamenorah" "So did he make the Menorah" which is fitting for the tribe of Levi.⁶ of the tribe of Levi did not take part in the offering of the Nesi’im. His lighting of the Menorah was his part in the dedication. See Rashi. (Numbers 8:2)

footnotes: ¹ See Chapter 22. ² See Chapter 198:14. ³ Shulchan Aruch ⁴ This custom is not very widespread in our times, except among Chassidim. ⁵ The leader of each tribe was called Nasi ⁶ Aaron, the High Priest, and Nasi

[During the month of Nisan,] we do not fast even the fast of a Yahrzeit,⁷ 429:2) This is our custom; but Shulchan Aruch permits a private individual to fast during Nisan. but we may fast because of a dream.⁸ The firstborn (males) fast on erev Pesach, as will be explained, God willing, in Chapter 113. A groom and a bride also fast during Nisan,⁹ 573) Refraining from fasting during Nisan is not a halachah, but a custom, and this fast overrides it. (poskim) even on Rosh Chodesh Nisan.¹⁰ 573. This is so only on Rosh Chodesh Nisan, because two of Aaron’s sons (Nadav and Avihu) died on that day. On any other Rosh Chodesh, the bride and groom may not fast. (Magein Avraham, Mishnah Berurah 573:9)

footnotes: ⁷ The anniversary of the death of one’s father or mother. (See Ramah ⁸ If one has a particularly onimous and disturbing dream, fasting with repentance helps to nullify the decree indicated by the dream. ⁹ Since it is a day of atonement for them, they fast the day of the wedding until the marriage ceremony takes place. (Magein Avraham ¹⁰ Ramah

On Shabbos Hagadol¹¹ is so called because in Egypt, the Jews were commanded to take a lamb on the tenth day of Nisan and designate it for the paschal offering. They did so, and tied the sheep to their bedposts. The Egyptians, upon hearing the Jews were bringing the sheep as a sacrifice, did not protest, even though the lamb was the Egyptian idol. That year, the tenth day of Nisan occurred on Shabbos, and in commemoration of this miracle, we call it Shabbos Hagadol—the Great Shabbos. (Tur 430 etc.) at Minchah it is customary not to recite Barchi Nafshi, but to say instead Avadim Hayinu¹² of Pesach. It is customary to recite until Lechappeir al Kol Avonoseinu (to atone all our sins). (Ramah 430) The Vilna Gaon did not agree with this custom, and many people follow his ruling and do not say it. etc., because on Shabbos Hagadol the redemption from Egypt and the miracles began.¹³

footnotes: ¹¹ The Shabbos before Pesach ¹² This is found in the Hagaddah ¹³ See note 11.