Reference for Yevamot 160:11

Rebbi Ḥiyya in the name of Rebbi Joḥanan: These are the words of Rebbi Eliezer, Rebbi Aqiba, and Rebbi Joshua. But the words of the Sages are that neither the castrate by human action nor the congenital castrate is able to perform ḥalîṣah nor does one perform ḥalîṣah for his wife²²²The Babli, 80b, disagrees and holds that Mishnah 5 explains Mishnah 4 and refers only to the congenital castrate who parallels the she-ram, following R. Aqiba.. He cannot perform levirate, nor does one marry his wife in levirate. That is the Mishnah: “The castrate who performed ḥalîṣah for his sister-in-law did not disable her; if he copulated with her, he disabled her because it is incestuous.” The hermaphrodite who performed ḥalîṣah for his sister-in-law did not disable her; if he copulated with her, he disabled her because it is incestuous²²³The Tosephta, 2:6 and 11:2, equates all rules of the hermaphrodite with those of the congenital castrate. It seems that this tradition (ascribed to Rebbis Yose and Simeon in the next Mishnah) considers the hermaphrodite as a congenitally infertile male.. “Similarly, if the brothers performed ḥalîṣah for a she-ram, they did not disable her; if they copulated with her, they disabled her because it is incestuous.”