The Chinuch notes that the origin of the mitzvah of Brit Milah appears in Sefer Breishit (17:10). The Pasuk states, “This is the covenant that you should guard, between me, you, and your offspring, to circumcise all males”.
He further notes another Pasuk located in Vayikra (12:3) that teach us our obligation to perform Milah. The Minchat Chinuch states that we can learn from this that Bnei Keturah are not obligated to perform Priyah, pulling back the foreskin flesh. How is this be deduced? The Mitzvah of Milah was commanded to all descendants of Abraham. The Rambam explains that Priyah is a Halacha LiMoshe MiSinai. Hence, the obligation does not apply to Bnei Keturah.
Milah is, generally speaking, performed even on Shabbat. The Torah Temimah states that an Androgonit is Chayav in Milah since the Pasuk states Kol Zachar, thereby including any male. However, the Milah of an Androgonit is never performed on Shabbat. Regarding the consequence for failing to perform circumcision, the Hebrew word Kol is omitted. Thus an Adrogonit does not transgress the Issur Karet, but only a Lav. His Milah is not done on Shabbat since he does not face the consequence of Karet for failing to fulfill the Mitzva of Milah.
These insights display the perfection of the Torah, in which not one letter let alone word is extra. From one three letter word, Kol, we derive two halachot, and are so convinced of the Drashot, we allow a potential Issur Karet and a Chiyuv Sekilah on this basis.
In the Zechut of our extra precautions observed in regard to Milah, may we be Zoche to soon see the arrival of the Mashiach.