Tex. Educ. Code § 53A.40

Bonds issued under this chapter and the record relating to their issuance shall be submitted to the attorney general, and if he finds that they have been issued in accordance with this chapter and constitute valid and binding obligations of the authority and are secured as recited therein he shall approve them, and they shall be registered by comptroller of public accounts who shall certify the registration thereon. Thereafter, they are incontestable. The bonds shall be negotiable and shall contain the following provision: "The holder hereof shall never have the right to demand payment thereof out of money raised or to be raised by taxation."