The chancery court or the chancellor in vacation, when he deems it to the best interest of the estate, may authorize the administrator, executor, or testamentary trustee to renew for a specified time any obligation of the deceased and, if such obligation be secured by encumbrance on any property, to renew such encumbrance upon such property. If it be shown to the interest of the estate, such chancery court or chancellor in vacation may direct said administrator, executor, or testamentary trustee to obtain money to pay off said obligation or encumbrance and to execute a new obligation or encumbrance to secure said money; and such obligation or encumbrance extended, renewed, or made shall be a valid charge on the estate or the property included in said encumbrance. Such encumbrance, whether renewed, extended, or made, shall not include any other property not embraced in the pre-existing encumbrance.