Cap. II Sol. Arg. 7 close: hortations keep elect persevering — scripture proofs of foresight-election end
Last, on the wording itself: Augustine (On Rebuke and Grace 13) says these lines are spoken to saints who will persevere as if their perseverance were unsure — they need to hear it that way, not to be proud but to fear. So the elect get such warnings not because their predestination is shaky or hangs on free will's change, but because by exhortation and other means God knows fit, he makes them persevere in grace and holiness. Those are the main Scripture proofs used for election from foresight of merits. Any further texts take their sense from these. From the texts, then, to the adversaries' reasons.
Latin
Postremo, quod attinet ad ipsorum verborum formulam, recte Augustinus, De corrept. & grat. cap. 13. Perseveraturis sanctis sic ista dicuntur, quasi eos perseveraturos habeatur incertum: non aliter enim hoc audire debent, quibus expedit non altum sapere, sed timere. Hujusmodi ergo hortationes ipsis electis adhibentur, non quod incerta sit illorum praedestinatio, aut ex mutabilitate arbitrii illorum pendula, sed quod hoc medio hortationum, aliisque quae Deus apta esse novit, efficiat ut in gratia & sanctitate perseverent. Atque haec praecipua testimonia Scripturarum sunt, quae ad probandam electionem ex praevisione meritorum afferuntur. Si quae alia occurrant, ex hisce quae explicata sunt veram illorum sententiam desumere in promptu erit. A testimoniis ergo ad rationes adversariorum veniamus.