Surah 21. Al-Anbiya, Ayah 87

I.e., the Prophet Jonah, who is said to have been swallowed by a "great fish", as mentioned in {37: 139} ff. and more fully narrated in the Old Testament (The Book of Jonah).

According to the Biblical account (which more or less agrees with the Qur'anic references to his story), Jonah was a prophet sent to the people of Nineveh, the capital of Assyria. At first his preaching was disregarded by his people, and he left them in anger, thus abandoning the mission entrusted to him by God; in the words of the Qur'an ({37: 140}), "he fled like a runaway slave". The allegory of his temporary punishment and his subsequent rescue and redemption is referred to elsewhere in the Qur'an (i.e., in {37:139-148}) and explained in the corresponding notes. It is to that punishment, repentance and salvation that the present and the next verse allude. (The redemption of Jonah's people is mentioned in 10:98 and {37:147-148}.)

Lit., "I was among the wrongdoers".

 Or “thinking We will let him get away with it.” Jonah (ﷺ) had been met with denial for many years. When he sensed the coming of Allah’s torment, he abandoned his city without Allah’s permission. Eventually, his people repented before the coming of the torment, and Allah accepted their repentance (see 10:98), whereas Jonah ended up in the belly of the whale (see 37:140-148).

 The darkness of the night, the sea, and the belly of the whale.

Zun-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. He was the prophet raised to warn the Assyrian capital Nineveh. For Nineveh see n. 1478 to x. 98. His story is told in xxxvii. 139-149. When his first warning was unheeded by the people, he denounced Allah's wrath on them. But they repented and Allah forgave them for the time being. Jonah, meanwhile, departed in wrath, discouraged at the apparent failure of his mission. He should have remained in the most discouraging circumstances, and relied on the power of Allah; for Allah had power both over Nineveh and over the Messenger He had sent to Nineveh. He went away to the sea and took a ship, but apparently the sailors threw him out as a man of bad omen in a storm. He was swallowed by a big Fish (or Whale), but in the depth of the darkness, he cried to Allah and confessed his weakness. 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.