21. "O my Lord! I seek refuge with You from asking You that of which I have no knowledge. And unless You forgive me and have Mercy on me, I would indeed be one of the losers". [11:47]

Whose supplication is this?

السلام عليكم ورحمة الله وبركاتة       

ﺑِﺴْـــــــﻢِﷲِﺍﻟﺮَّﺣْﻤَﻦِﺍلرَّﺣِﻴﻢ

Answer:

Prophet Nuh (as)

Explanation:

Allah sent Nuh (AS) to his people as a Prophet. He remained among them a thousand years minus fifty years” (29:14)

He called his people night and day, openly, publicly and privately. But his people thrust their fingers into their ears, covered themselves up with their garments, and persisted in their denial, magnified with  pride. And they have plotted a mighty plot to exile or kill him.

And Nuh (AS) said: “My Lord! Leave not one of the disbelievers on the earth! If You leave them, they will mislead Your slaves, and they will beget none but wicked disbelievers.” [11:26 & 27]

He invoked his Lord to help him against his people. Allah Subhanahutha’ala said to him: “None of your people will believe except those who have believed already. So be not sad because of what they used to do." [11:36]

“And construct the ship under Our Eyes and with Our Inspiration, and address Me not on behalf of those who did wrong; they are surely to be drowned.” [11:37]

And as he was constructing the ship, they made a mockery of him. He said: “If you mock at us, so do we mock at you likewise for your mocking.And you will know who it is on whom will come a torment that will cover him with disgrace and on whom will fall a lasting torment.”  [11:38 & 39]

When Allah commanded the oven to overflow, he boarded  the ship from each creature two mates and his family and followers and say, ‘Praise to Allah who has saved us from the wrongdoing people.’

(23:27-28)

So it (the ship) sailed with them amidst the waves like mountains, and Nuh (AS) called out to his son, who had separated himself (apart), “O my son! Embark with us and be not with the disbelievers.”

[11:42]

The son replied: “I will betake myself to a mountain, it will save me from the water.” Nuh (AS) said: “This day there is no saviour from the Decree of Allah except him on whom He has mercy.” And a wave came in between them, so he (the son) was among the drowned. [11:43]

And Nuh (AS) called upon his Lord and said, “O my Lord! Verily, my son is of my family! And certainly, Your Promise is true, and You are the Most Just of the judges.” [11:45].

Allah said: “O Nuh (AS)! Surely, he is not of your family; verily, his work is unrighteous, so ask not of Me that of which you have no knowledge! I admonish you, lest you be one of the ignorants.” [11:46]

Nuh (AS) said: “O my Lord! I seek refuge with You from asking You that of which I have no knowledge. And unless You forgive me and have Mercy on me, I would indeed be one of the losers.” [11:47]

As a loving father, Nuh (AS) could not save his own son who was drowned infront of his eyes. Allhuthala already told to Nuh (AS), "Address Me not on behalf of those who did wrong; they are surely to be drowned."

He was regretting much for pleading about his son to Allah Subhanshuthala.  He did not have knowledge about his  son's belief. But All Knower Allah very well knew about his unrighteous work. Always Allah’s decrees are absolutely just and final. Nuh (AS) asked pardon to forgive  and to shower His Mercy upon himself.

الحمدلله