Where a municipality enters into an agreement for the acquisition of a capital asset without complying with the peremptory requirements of section 19 of the Local Government: Municipal Finance Management Act 56 of 2003 (MFMA) - including council approval of the capital project, appropriation of funds in the capital budget, and availability of funding - such agreement is ultra vires, null and void, and unenforceable ab initio. The doctrine of legality, as a fundamental constitutional principle, requires strict compliance with peremptory statutory provisions governing the exercise of public power. Neither the doctrine of estoppel nor the Turquand rule can validate a transaction that is ultra vires or contrary to peremptory statutory requirements. A municipal council resolution that merely approves a commitment letter from a provincial department does not constitute approval of a capital project as required by section 19(1)(b) of the MFMA. The principle of legality trumps the protection of innocent third parties in contracts with municipalities where there has been non-compliance with peremptory statutory provisions.