Ketubot, Chapter Six, Mishnah Seven
This mishnah discusses a father who set aside a sum of money for his daughter for her to use for a specific purpose and then died or went away. The question is, when the daughter gets married, can the trustee give it to her husband and allow him to use it for a different purpose.
1) If a man deposited a sum of money with an agent for his daugher, and [after she was betrothed] she says, I trust my husband, the trustee must act in accordance with the condition of his trust, the words of Rabbi Meir.
2) Rabbi Yose says: were [the trust] a field and she wished to sell it, it would be as if it was sold immediately!
3) To whom does this apply? To [a daughter] who has reached majority age, but in the case of a minor, there is no validity at all to the act of a minor.
Section one: As explained above, the father gave money to an agent to be used for his daughter for a specific purpose, for instance to buy a field. Now that the father is no longer there and the daughter has been married, she wants the husband to receive the money, for she trusts him. According to Rabbi Meir the agent must do whatever the father told him to do. The Talmud explains that this is because it is a commandment to fulfill the wishes of a dead person.
Section two: Rabbi Yose responds that even if the agent had already bought the field which the father wanted him to buy, and the daughter now had possession of the field, she could sell it and give the money to her husband. Therefore, there is no reason for the agent to buy the field and give it to her, rather he can give her directly the money for her to give to her husband.
Section three: The debate between Rabbi Meir and Rabbi Yose is only with regard to a daughter who has reached majority age. At this age she could have sold the field, and therefore Rabbi Yose holds that the money is given to her husband. However, if she is still a minor she cannot engage in business. Even if the agent had bought her the field, she could not have sold it. Since Rabbi Yoses reasoning is not applicable in this case, the agent must do what he was told to do by the father.