Kesuvos8: 2
רַבִּי שִׁמְעוֹן חוֹלֵק בֵּין נְכָסִים לִנְכָסִים: נְכָסִים הַיְדוּעִים לַבַּעַל — לֹא תִמְכֹּר; וְאִם מָכְרָה וְנָתְנָה — בָּטֵל. שֶׁאֵינָן יְדוּעִים לַבַּעַל — לֹא תִמְכֹּר; וְאִם מָכְרָה וְנָתְנָה — קַיָּם.
R’ Shimon distinguishes between one kind of property and another: Property that is known to the husband —- she may not sell; if she sold [it] or gave [it] away, [the act] is invalid. [Property] unknown to the husband —- she may not sell; but if she sold [it] or gave [it] away, [the act] is valid.