Some parents think that when a child reaches the age of 20, the obligations of parenthood end. The son or daughter is now a mature adult who can, and must, learn to fend for his or herself.
However, we can learn from the conduct of Avraham that education never ceases. At this point, Yitzchak was 37 years old, and Avraham could have quite reasonably taken a "back seat," allowing Yitzchak to make his own choices about where to live and whom to marry.
In fact, Avraham did precisely the opposite. Instead of relaxing and enjoying his own life, he relinquished his life's savings and all his possessions, giving them to Yitzchak in an attempt to help him find an appropriate wife.
From this we can learn that parenthood never ends. Even when our children become mature adults, we should be willing to sacrifice everything that we have for their benefit.
(Basde on Sichas Shabbos Parshas Chayei Sarah 5730)