All the month of Nissan1 one does not say ''Tachanun''2
nor ''Tziduk HaDin''.3
Also, one does not say ''Your righteousness is an everlasting righteousness'' in the Shabbat afternoon service.
It is customary from Rosh Chodesh (Nissan) onwards to read every day
the paragraph (in the Torah) for the prince (of the tribe) who had brought his offerings on that day (of Nissan).4
On the thirteenth day (of Nissan) one reads5 the portion ''Beha'alotecha''
up to6 ''So he made the menorah'' which is for the tribe of Levi.1) The month of Nissan is considered a time of joy because it is the month during which the Israelite nation was liberated from slavery in Egypt. It is also the month during which the ''Mishkan'' (the portable ''temple'' used while the Jews were travelling through the desert) was first erected and dedicated.
2) Prayers of supplication which are said after the ''Amidah'' during the morning and afternoon service.
3) A prayer said at the cemetery during a funeral.
4) The ''Mishkan'' was set up on the first of Nissan, and on each of the first 12 days of Nissan during that year, a prince of a different tribe brought his offerings as part of the dedication of the Altar. See Num. Ch. 7.
5) Num. 8:1.
6) Num. 8:4.
כל חודש ניסן אין אומרים תחנון
ולא צדוק הדין
ואין אומרים צדקתך בשבת במנחה
נוהגין מראש חודש ואילך לקרות בכל יום
פרשת הנשיא שהקריב בו ביום
וביום שלשה עשר קורין פרשת בהעלתך
עד כן עשה את המנורה שהוא נגד שבטו של לוי We do not fast on it (not) even a fast on the (anniversary) Yahrzeit 1
but one does fast the fast (for a bad) dream.
The firstborn fast on the eve of Pesach,
as will be explained, with G-d's help, in Ch. 113.
The groom and bride also fast on it,2
even if (their wedding day is) Rosh Chodesh Nissan.31) Of one's parents death.
2) It is the custom for the couple to fast on their wedding day, since this is considered as a personal ''Day of Atonement'' when all their sins are forgiven and they start their new life together with a clean sheet.
3) Normally, the couple should not fast on a New Moon, but Nissan is different because the two sons of Aharon, Nadav and Avihu) died on Rosh Hodesh Nissan in the desert (Mishna Berura 573:9).
אין מתענין בו אפילו תענית יום זכרון
אבל תענית חלום מתענין
והבכורים מתענין בערב פסח
כאשר יבואר אם ירצה השם בסימן קי''ג
וחתן וכלה גם כן מתענין בו
ואפילו בראש חודש ניסן On Shabbat HaGadol1 at Mincha, it is customary not to say
''Bless the Lord, O my soul...''2 rather (one reads from the Haggadah) ''Slaves we were...''
because on Shabbat HaGadol was the start of the redemption (from Egypt) and the miracles.31) lit: ''the Great Shabbat''. This is the Shabbat immediately before Pesach.
2) Psalm 104.
3) The miracles during the final week in Egypt.
בשבת הגדול למנחה נוהגין שאין אומרים
ברכי נפשי אלא עבדים היינו וכו'
לפי שבשבת הגדול היתה התחלת הגאולה והנסים