1. The Mitzvah of Milah:[1]

It is a positive command in the Torah for a father to circumcise his son.[2] [Although this Mitzvah is applicable to the general Jewish public, and to the individual in the event that he was not circumcised, as explained in Halacha 3, nonetheless, there is a special command on the father for him to perform the Bris, in addition to the general Mitzvah for the child to be circumcised.[3] The Mitzvah of Mila contains three parts, the actual circumcision, the fact the individual is now circumcised, and the fact that the individual is no longer considered uncircumcised.[4] The Mitzvah of Mila is constant, and hence once one becomes circumcised he fulfills the Mitzvah for every moment of his life thereafter.[5]]

The greatness of the Mitzvah:[6] The Mitzvah of Mila is the greatest command in the Torah.[7]

No Gehenom:[8] Abraham our forefather stands [in the opening of Gehennom] and selects those who are circumcised and does not allow them to enter. 

Remembering the Mila daily: Some Poskim[9] write that in addition to the mitzvah to perform the circumcision, there is also a mitzvah to remember the circumcision daily. The purpose of this remembrance is in order so he remember that he is a servant of G-d and bears a symbol of such on his body. This will help the individual not rebel against G-d and not view himself as emancipated.

Celebrating the day of one’s Bris:[10] In some communities it is customary to make a celebratory meal each year on the day in which one’s Bris took place. The Ben Ish Chaiy records this custom and writes that it is a good custom and he is very fond of it although he personally does not follow it in his family. Nonetheless, he is accustomed annually on the day of his Bris to say a short prayer to Hashem mentioning the fact that he entered the Bris of Abraham Avinu on this day.

[1] Michaber Y.D. 260:1; Kiddushin 29a; Rambam Sefer Hamitzvos Mitzvah 215; Shevach Habris 7:1; See Likkutei Sichos Vol. 30 Lech Licha 3^rd Sicha; Pesakim Uteshuvos 260:1; See Encyclopedia Talmudit Vol. 46 Erech Mila p. 399-401, 405-406, 413-414, 442-448 footnotes 1-16 and 58-64, 123-138

[2] The source: The Rambam in Sefer Hamitzvos lists the Mitzvah from the verse in Parshas Lech Licha regarding Avraham Avinu. However, in his Minyan Hamitzvos Mitzvah 215 he writes the source is from the verse in Parshas Tazria. See Likkutei Sichos ibid that the actual obligation is learned from the mitzvah in Parshas Tazria, which was given after Matan Torah, while the background and details and purpose of the mitzvah are learned from Parshas Lech Licha. See Encyclopedia Talmudit ibid

[3] Likkutei Sichos ibid; See Encyclopedia Talmudit Vol. 46 Erech Mila p. 399; 405-408

[4] Likkutei Sichos 3:761, printed in Shaareiy Mila 2; See Tzafnas Paneiach on Rambam Hilchos Mila; Ragatchaver Gaon; See Encyclopedia Talmudit Vol. 46 Erech Mila p. 402-403 footnotes 33-43

[5] See Menachos 43b; Hisvadyus 5748 1:424; Shaareiy Mila 16

[6] Michaber and Rama Y.D. 260:1; Nedarim 32a; Levush 260:1; Pesakim Uteshuvos 260:2; See Encyclopedia Talmudit Vol. 46 Erech Mila p. 402-403 footnotes 33-43

Other opinions: Some Poskim rule that this is with exception to the Mitzvah of Tzitzis which is even greater than the Mitzvah of circumcision. [Poskim brought and negated in Yad Avraham 260]

[7] The reason: As we find the penalty of excision given for a man who does not circumcise himself once he has reached adulthood. [Shach 260:1] Likewise, there were 13 covenants that were made over this command, as the word covenant [i.e. Bris] is written 13 times regarding this mitzvah. [Beis Yosef 260; Mishneh Nedarim 3:11] Likewise, the circumcision is the only mitzvah that is engraved within our very body on a constant basis. [Levush ibid] Likewise, we find that it pushes off the prohibition of Shabbos. [Yad Avraham 260; Mishneh Nedarim 3:11]

[8] Taz 263:3; Tur 260; Eiruvin 19a; See Pesakim Uteshuvos 260:2 footnote 30

[9] Sefer Chareidim 44

[10] See Ben Ish Chaiy Parshas Reiy 17; Afrasakta Deanya 123 footnote 2 in name of Chasam Sofer