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