must express that intent in specific terms [] within the four corners of the contract." Ethyl Corp., 725 S.W.2d at 708; see also Fisk Elec. Co. v. Constructors & Assocs., 888 S.W.2d 813, 813-14 (Tex. 1994); Spaw Glass, Inc. v. E.T. Servs., Inc., 143 S.W.3d 897, 899 (Tex. App.-Beaumont 2004, pet. denied) (per curiam) ("The express negligence rule requires that the intent of the party seeking indemnity from the consequences of that party's own future negligence must be expressed in unambiguous terms within the four corners of the contract.").