What is the ruling on quoting a verse, in writing or verbally, without indicating that it is from the Quran or saying, "Allah the Almighty has said"?

There is no harm in mentioning a verse or a part of it without stating "Allah Almighty says," as it was narrated that the Prophet, peace and blessings be upon him, used to mention the verses of piety in his sermons without stating that, as in the Hadith of Khutbat al-Haja (the Sermon of Need), and in the Prophet's letter to Heraclius.