Section 118
SEC. 118. Except in favor of the Government or any of its branches, units, or institutions, lands acquired under free patent or homestead provisions shall not be subject to encumbrance or alienation from the date of the approval of the application and for a term of five years from and after the date of issuance of the patent or grant, nor shall they become liable to the satisfaction of any debt contracted prior to the expiration of said period, but the improvements or crops on the land may be mortgaged or pledged to qualified persons, associations, or corporations. No alienation, transfer, or conveyance of any homestead after five years and before twenty-five years after issuance of title shall be valid without the approval of the Secretary of Agriculture and Commerce, which approval shall not be denied except on constitutional and legal grounds.