Yevamos 6:6 - 7:1

ב"ש אומרים שני זכרים – that we derive it from Moses who separated from [his] wife afer two males were born to him.

וב"ה אומרים זכר ונקיבה – as it states (Genesis 5:2): “male and female He created them.” But from Moses, it is not a proof because he acted following the Divine order.

ושהה עמה עשר שנים וכו' – as we find with Abraham after he tarried with his wife for ten years without her giving birth, he married Hagar and for the days that he lived with her outside the Land [of Israel], the did not count in the number, for perhaps dwelling outside of the land caused it, and all the days that the husband or the wife are sick or are imprisoned and in a similar manner we speak that they prevent sexual intimacy, they do not count to the number of ten years.

גרשה מותרת לינשא לאחר – for perhaps it was not her, but rather him [who was infertile], and when he divorces her, he gives her the Ketubah settlement if she claims that it is from him [who was infertile] who does not have a spermatic emission which does not shoot forth like an arrow (i.e., does not fructify), and they place an oath upon her if she knows that he does have a spermatic emission which does shoot forth like an arrow , and she makes against him false claim which is a lie.

האיש מצווה על פריה ורביה ולא האשה – as it is written (Genesis 1:28): “Be fertile and increase, [fill the earth] and master it,” and [the word] "כבשה" is written without a “VAV.” It is the way for a man to conquer the woman; he is commanded on “being fertile and increase.”

רבי יוחנן בן ברוקה אומר וכו' – But the Halakha is not according to him.

אלמנה לכ"ג: עבדי מלוג – what the woman leaves for herself and does not write in her Ketubah is called

נכסי (עבדי) מלוג – a wife’s estate of which the husband has the fruition without responsibility for loss or deterioration - that the husband “plucks” that property like the plucking of chickens because he consumes the fruits of those properties and if they lessened [In value] they lessened for her, and if they increased, they increased for her. But נכסי צאן ברזל (mort-main, the wife’s estate held by her husband, which, in the case of her death or divorce, he must restore “in specie,” being responsible with all his landed property for loss or deterioration) – they are the properties that she brought in to him and what he adds to it is hers, and they wrote into the Ketubah: the total amount that so-and-so accepted upon himself is such -and such, in her Ketubah, and therefore, they are called צאן ברזל – as the principal exists like iron, and if everyone died, the husband is liable to because they are accustomed to place the sheep in such-and-such an appraisement of valuables (brought into the marriage by the wife) , and the shepherd would be responsible for them (if lost), according to the estimate even if all the sheep died, hence, they are called properties that the husband accepts responsibility for - נכסי צאן ברזל (that must be returned to the wife “in specie” in the event of death or divorce.