Bava Batra 136 - A Will of a Healthy Person
While a seriously ill person can transmit his last-will instructions orally, though not in writing, a healthy person lacks both of these options. However, one of the ways to accomplish property transfer is to give over the title to the possessions now, but the right to use them only after death.
When one writes his properties over to his sons for use after death, he must indicate this by including the clause "from today and after death" - says Rabbi Yehudah. But Rabbi Yossi says that it is enough to write "after death," and the date on the document indicates that he means "from today."
In such a case, the father cannot sell the properties completely, because they are written over to his son, and the son cannot sell them, because they are in the possession of the father.
Art: Emile Friant - Sorrow