With regard to the aayah “La ilaaha illa anta subhaanaka innee kuntu min al-zaalimeen”, the following report has been narrated concerning its virtues:
Sa’d said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘The call of Dhoo’l-Noon [Yoonus/Jonah], which he recited when he was in the belly of the fish, ‘La ilaaha illa anta subhaanaka innee kuntu min al-zaalimeen. There is no Muslim who recites this in any situation, but Allaah will respond to him.” (Reported by al-Tirmidhi, 3427, and classed as saheeh in Saheeh al-Jaami’, 3383).
The Prophet (peace and blessings of Allaah be upon him) said: “Shall I not tell you of something which, if some of the misery and distress of this world befalls a man and he recites it, he will be relieved of his stress. It is the du’aa’ of Dhoo’l-Noon: ‘La ilaaha illa anta subhaanaka innee kuntu min al-zaalimeen.’” (Reported by al-Haakim; Saheeh al-Jaami’, 2605).