572. A Bris on Yom Tov

Milah 2:9                                                                        

If they forgot to bring a knife on Friday, one may ask a non-Jew to bring it on Shabbos so long as he does not carry it through the public domain. The general rule is that one may request a non-Jew to perform an activity that is prohibited because of shvus (to enforce rest) in order to perform a mitzvah at the appropriate time. However, if an activity is an actual form of proscribed labor, one may not request that a non-Jew perform it on Shabbos.

Milah 2:10

Preparations for a bris, even when performed at the appropriate time, do not override yom tov because they could have been done before yom tov started. Since such preparations do not override the rabbinic prohibitions against shvus on Shabbos, why would they override an actual prohibition of the Torah? However, one may grind medicinal herbs on yom tov because they are suitable for use as food. Similarly, the oil and wine may be mixed together on yom tov.