Siman 151

All those explained in siman 149 who do not have a chazakah and whose consumption of the produce is not proof—if they brought witnesses that the owners sold this field to them or gave it as a gift, their proof is valid proof and we establish the field in their possession, except for a gazlan. Even if he brought witnesses, it is not proof if they say that he admitted in their presence that he sold him this field or gave it to him, unless they saw the giving of the money, as will be explained. Similarly, a husband regarding his wife's property, her admission is nothing, for she can say, "I did it to please my husband," and I did not want to quarrel with him so that he would not say to me, "You have set your eyes on divorce or death." And even when they saw the giving of the money, it is nothing for this reason [as is evident from the Rashbam 49b, s.v. "teima," see there]. And regarding which property can she say this? Regarding nichsei tzon barzel that she brought in to him in her dowry, or if he bought from her the field that he designated for her in her ketubah in place of the money, or movables that she brought in to him in her dowry, and regarding a field that he wrote for her in her ketubah as an apotiki for the maneh or two hundred of the ketubah, and regarding a field that he gave her from his own as a tosefet ketubah. For in all these fields, since they are his, there would be animosity if she did not agree to his will, and even with a deed, it is nothing. But regarding nichsei melog, where the core of the land is hers even now and he only consumes the fruits, he has proof when he brought witnesses that she sold or gave it to him, and even if she admitted in their presence that she sold or gave it to him. For in this, even if she did not agree, he would not have animosity or a quarrel with her, unlike the one who disagrees in this.

And a woman regarding the property of her husband where she brought witnesses that he sold it to her, it was explained in Even HaEzer siman 85 that if she purchased it with hidden funds, her acquisition is nothing, for the husband can say that he desired to extract from her the funds that she hid from him, and even if he wrote a deed for her, it is nothing. And if she purchased it with revealed funds, her acquisition is an acquisition. And if he gave it to her as a gift, she has acquired it. And further details of this law were explained there in section 44, for according to the Rambam there is another opinion in this matter:

How is a gazlan defined? Once he has been established as a gazlan regarding this field, even if he brought proof via a deed that the owners admitted before witnesses that they sold the field to him, and it is written in the deed that he took the money, but it is not written therein that the witnesses testified that they saw the giving of the money, and the owners say, "I did not sell it to him at all and I did not take money, but only because of fear did I admit to him," we remove the field from his possession and he has nothing. And if the witnesses testified that in their presence he counted out such and such money to him, we remove the field from the hand of the gazlan and the owners return the money to him. And even though there is no delivery of a moda'ah before us, for regarding a gazlan there is no need for the delivery of a moda'ah, as the duress is known. This is the opinion of the Rambam, of blessed memory. However, the Rosh, of blessed memory, disagrees on this and holds that if the witnesses saw the giving of the money and the seller did not deliver a moda'ah beforehand, his sale is a sale, for we maintain "if they hung him and he sold, his sale is a sale," as written in siman 205, and there it will be explained. Our teacher, the Rema, ruled accordingly. And any gazlan who was not established as a gazlan except regarding this field has a chazakah in another field, for regarding this field he risks his life and they are afraid of him. But if he was established as a gazlan regarding all things, he has no chazakah or proof in any place. And there is no difference between a gentile gazlan and an Israelite gazlan [it appears to me]. And if a guarantee of property is written in the deed, some say that he acquired it when he was not established as a gazlan except regarding this field, for they are not so afraid of him as to lien property to him as well. But where he was established as a gazlan for all things, there is no proof even with a lien on property [Sma]. And the guarantee regarding a woman and her husband was explained there.