فَاسْتَجَبْنَا لَهُ وَنَجَّيْنَاهُ مِنَ الْغَمِّ
So `We answered his call, and delivered him from the distress.
means, `We brought him forth from the belly of the fish and from that darkness.'
...
وَكَذَلِكَ نُنجِي الْمُوْمِنِينَ
And thus We do deliver the believers.
means, when they are in difficulty and they call upon Us and repent to Us, especially if they call upon Us with these words at the time of distress.
The leader of the Prophets encouraged us to call upon Allah with these words.
Imam Ahmad recorded that Sa`d bin Abi Waqqas, may Allah be pleased with him, said;
"I passed by Uthman bin Affan, may Allah be pleased with him, in the Masjid, and greeted him. He stared at me but did not return my Salam.
I went to Umar bin Al-Khattab and said;`O Commander of the faithful, has something happened in Islam!' I said that twice.
He said, `No, why do you ask?'
I said, `I passed by Uthman a short while ago in the Masjid and greeted him, and he stared at me but he did not return my Salam.'
Umar sent for Uthman and asked him, `Why did you not return your brother's Salam?'
He said, `That is not true.'
Sa`d said, `Yes it is.'
It reached the point where they both swore oaths. Then Uthman remembered and said, `Yes, you are right, I seek the forgiveness of Allah and I repent to Him. You passed by me a short while ago but I was preoccupied with thoughts of something I had heard from the Messenger of Allah, which I never think of but a veil comes down over my eyes and my heart.'
Sa`d said;`And I will tell you what it was. The Messenger of Allah told us the first part of the supplication then a Bedouin came and kept him busy, then the Messenger of Allah got up and I followed him. When I felt worried that he would enter his house, I stamped my feet. I turned to the Messenger of Allah , who said,
مَنْ هَذَا أَبُو إِسْحَاقَ
Who is this Abu Ishaq?
I said, "Yes, O Messenger of Allah."
He said,
فَمَه
(What is the matter)?
I said, "Nothing, by Allah, except that you told us the first part of the supplication, then this Bedouin came and kept you busy."
He said,
نَعَمْ دَعْوَةُ ذِي النُّونِ إِذْ هُوَ فِي بَطْنِ الْحُوتِ
Yes, the supplication of Dhun-Nun when he was in the belly of the fish;
لااَّ إِلَـهَ إِلااَّ أَنتَ سُبْحَـنَكَ إِنِّى كُنتُ مِنَ الظَّـلِمِينَ
There is no God but You, Glorified be You! Truly, I have been of the wrongdoers.
فَإِنَّهُ لَمْ يَدْعُ بِهَا مُسْلِمٌ رَبَّهُ فِي شَيْءٍ قَطُّ إِلاَّ اسْتَجَابَ لَه
No Muslim ever prays to his Lord with these words for anything, but He will answer his prayer."
It was also recorded by At-Tirmidhi, and by An-Nasa'i in Al-Yawm wal-Laylah.
Ibn Abi Hatim recorded that Sa`d said that the Messenger of Allah said;
مَنْ دَعَا بِدُعَاءِ يُونُسَ اسْتُجِيبَ لَه
Whoever offers supplication in the words of the supplication of Yunus, will be answered.
Abu Sa`id said;
"He was referring to;
وَكَذَلِكَ نُنجِي الْمُوْمِنِينَ
(And thus We do deliver the believers).