with regard to the contention that said resolution can not nullify the contractual obligations assumed by the defendant-appellee referring to the restrictions incorporated in the deeds of sale and later in the corresponding transfer certificates of title issued to defendant-appellee it should be stressed , that while non-impairment of contracts is constitutionally guaranteed , the rule is not absolute , since it has to be reconciled with the legitimate exercise of police power , i.e. , `` the power to prescribe regulations to promote the health , morals , peace , education , good order or safety and general welfare of the people . '