˹making it˺ perfectly upright, to warn ˹the disbelievers˺ of a severe torment from Him; to give good news to the believers—who do good—that they will have a fine reward,
Both end with giving glad tidings to the believers but 17:9 uses 'yubashiru' (indicative) while 18:2 uses 'yubashira' (subjunctive) — a single vowel difference in the verb form.