Allah is good, Allah has attribute of speech, the Quran is speech of Allah. Therefore the Quran is good.

> O people, **Allah is Good** and He therefore, accepts only that which is good.
https://sunnah.com/muslim/12/83

Angels say Allah spoke truth.

>What is it that your Lord has said?" They will say: "The Truth; and He is the Most High, the Most Great."" (Qur'an 34:23)

Isn't True speech good?