21:86-87
21:86
We admitted them to Our mercy: for they were of the righteous ones.
21:87
And remember Zun-nun, when he departed in wrath: He imagined that We had no power over him! But he cried through the depths of darkness, “There is no god but thou: glory to thee: I was indeed wrong!”
Dhu al Nun. “the man of the Fish or the Whale”, is the title of Jonah (Yunus), because he was swallowed by a large Fish or Whale. The “darkness” may be interpreted both physically and spiritually; physically, as the darkness of the night and the storm and the Fish’s body; spiritually as the darkness in his soul, his extreme distress in the situation which he had brought on himself. Allah Most Gracious forgave him. He was cast out ashore; he was given the shelter of a plant in his state of mental and physical lassitude. He was refreshed and strengthened, and the work of his mission prospered. Thus he overcame all his disappointment by repentance and Faith, and Allah accepted him
References:
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 21 verse 87).