What is the virtue of saying: "There is no deity except You; glory be to You. Indeed, I have been of the wrongdoers," and is it great?

The saying: "There is no deity except You; glory be to You. Indeed, I have been of the wrongdoers" is a great supplication through which Allah responds to whoever supplicates with it for anything. Many texts have been mentioned in the Quran and Sunnah regarding the virtue of seeking forgiveness, among them is the saying of Allah the Almighty: "And said, 'Ask forgiveness of your Lord. Indeed, He is ever Forgiving. He will send [rain from] the sky upon you in [abundance]. And give you increase in wealth and children and make for you gardens and make for you rivers.'" And the saying of the Prophet, peace and blessings be upon him: "Whoever adheres to seeking forgiveness, Allah will make for him a way out of every worry and a relief from every hardship, and will provide for him from where he does not expect." The Prophet, peace and blessings be upon him, used to seek forgiveness and repent more than seventy times a day. These remembrances have great virtue and much good, which is why the righteous predecessors used to recite them frequently.