In his actions, his hidden nature appears.

He whose element (essence) is not good

The good will not emerge from his mouth.

This is supported by the saying of the Almighty in Surah al-Aʿrāf:

{And the good land—its vegetation comes out by permission of its Lord; but that which is bad—it does not come out except sparsely [with difficulty].} (Al-Aʿrāf: 58).

This means that the believer, who is likened to the good land, performs righteous deeds and his knowledge is also righteous. As for the disbeliever, who is likened to the evil land, neither his knowledge nor his deeds are anything but evil.

And from the book al-Ṣāfī in the commentary of Surah al-Aʿrāf, from the Master Jaʿfar al-Ṣādiq, that he said:

"Indeed, the Quran has an outward and an inward. Everything that Allah has forbidden in the Quran is the outward, and the inward of that is the Imams of Injustice (Aʾimmat al-Jawr). Everything that Allah has permitted in the Book is the outward, and the inward of that is the Imams of Truth (Aʾimmat al-Ḥaqq)."

What also points to this meaning is what was established by Abū ʿAbdullāh Jalāl al-Dīn, known as Taqwīm al-Asmāʾ (The Rectification of Names), regarding the knowledge of the personages of the Earth and Heaven, saying: