30 ILCS 390/10

All Bonds issued in accordance with the provisions of this Act shall be direct, general obligations of the State of Illinois and shall so state on the face thereof, and the full faith and credit of the State of Illinois are hereby pledged for the punctual payment of the interest thereon as the same shall become due and for the punctual payment of the principal thereof at maturity, and the provisions of this Section shall be irrepealable until all such Bonds are paid in full as to both principal and interest.