First opinion: Durandus, all the natural precepts can be kept without grace
First, many of the older Schoolmen maintain that man in the state of corrupt nature can, by his own strength and without the help of special grace, keep each and every precept of the law of nature as to the substance of the works, and so achieve the whole of what they call moral good.
This is the view of Durandus on the second book of the Sentences, distinction 28, question 4. There he affirms, and tries to prove with several arguments, that a man without grace can fulfil God's precepts, those of natural law though not those of supernatural law. So he grants that someone might, without grace, be free of every sin of omission and of commission, though original sin would remain in him and would shut him out of salvation.
Latin
X. Et primo quidem multi ex veteribus Scholasticis pertendunt hominem in statu naturae corruptae posse propriis viribus, absque specialis gratiae auxilio, omnia & singula legis naturae praecepta servare quoad operum substantiam, & sic totum quod vocant morale bonum efficere. Haec est sententia Durandi in secundum sententiarum, distinctione vigesima octava, quaestione quarta. Ubi affirmat & aliquot argumentis probare contendit, aliquem sine gratia implere posse divina praecepta, quae, scilicet, sunt juris naturalis, non autem supernaturalis. Adeoque concedit fieri posse, ut absque gratia aliquis omni peccato careat, tam omissionis, quam commissionis, licet in eo maneat peccatum originale, propter quod foret salute excludendus.