הלכה על שבת 222:2

And that which they also said (Shabbat 111a) that one who castrates after [another] who castrates is liable, and like Rabbi Chiya bar Avin said that Rabbi Yochanan said, "Everyone concedes that one who leavens after [another] leavened is liable, as it is stated (Leviticus 6:10), 'It shall not be baked leavened,' and (Leviticus 2:11) 'it shall not be made leavened'; that one who castrates after [another] castrates is liable, as it is stated (Leviticus 22:24), 'And a crushed, and a pounded and a disconnected and a cut' - if one is liable for one cut, is one not all the more so [liable] for one disconnected? Rather, [this comes] to include that one who disconnects after one who cuts is liable." How is this? Behold, one came and cut the member, and another came and cut the testicles or disconnected them, the last one is also liable; and so [too,] if one came and crushed the member, and another came and disconnected it, they are all lashed - even though the last one does not castrate, as it is already castrated. And that which they, may their memory be blessed, said (Shabbat 111a) that if one neuters a female - whether a person or of the other species - he is exempt. And that which they said (Shabbat 110a) that [it] is forbidden to give a cup of roots to a man or to other creatures in order to sterilize them, but we do not administer lashes for this. And so [too,] one who places his fellow in water or in snow, until the power of his reproductive organs is neutralized, is not lashed until he castrates [him] manually. But it is fitting to strike [such a one with] lashes of rebellion. And a woman is permitted to drink a cup of roots that sterilize her, such that she not give birth; as women are not commanded about being fruitful and multiplying - as I wrote in the first commandment of the book. And the rest of its details are elucidated in [various] places in Tractate Shabbat and Yevamot (see Tur, Even HaEzer 5).