In discussing this passage, the scholars of Tafsir mention a story which is mostly based upon Isra'iliyat narrations. Nothing has been reported about this from the Infallible Prophet that we could accept as true. But Ibn Abi Hatim narrated a Hadith whose chain of narration cannot be regarded as Sahih because it is reported by Yazid Ar-Raqashi from Anas, may Allah be pleased with him. Although Yazid was one of the righteous, his Hadiths are regarded as weak by the Imams. So, it is better to speak briefly of this story and refer knowledge of it to Allah, may He be exalted. For the Qur'an is true and what it contains is also true.
فَفَزِعَ مِنْهُمْ
(he was terrified of them.) This was because he was in his Mihrab (private chamber). That was the noblest part of his house, where he commanded that no one should enter upon him that day. So, he did not realize that these two people had climbed the fence surrounding his Mihrab (private chamber) to ask him about their case.
وَعَزَّنِى فِى الْخِطَابِ
(and he overpowered me in speech.) means, `he defeated me.'
وَظَنَّ دَاوُودُ أَنَّمَا فَتَنَّـهُ
(And Dawud guessed that We have tried him) `Ali bin Abi Talhah reported that Ibn `Abbas said that this means, "We tested him."
وَخَرَّ رَاكِعاً وَأَنَابَ
(and he fell down prostrate and turned (to Allah) in repentance.)
فَغَفَرْنَا لَهُ ذَلِكَ
(So, We forgave him that,)
The performance of Sajdah in Surah Sad is not one of the obligatory locations; it is a prostration of thanks (Sajdat Shukr). The evidence for it is the report recorded by Imam Ahmad from Ibn `Abbas, may Allah be pleased with him, who said; "The prostration in Surah Sad is not one of the obligatory prostrations; I saw the Messenger of Allah ﷺ prostrating in this Surah." This was also recorded by Al-Bukhari, Abu Dawud, At-Tirmidhi, and An-Nasa'i in his Tafsir. At-Tirmidhi said, "Hasan Sahih." In his Tafsir of this Ayah, An-Nasa'i also recorded that Ibn `Abbas, may Allah be pleased with him, said, "The Prophet prostrated in Sad, and he said:
«سَجَدَهَا دَاوُدُ عَلَيْهِ الصَّلَاةُ وَالسَّلَامُ تَوْبَةً، وَنَسْجُدُهَا شُكْرًا»
(Dawud prostrated as an act of repentance and we prostrate as an act of thanks.)" This was recorded only by An-Nasa'i. The men of its chain of narration are all reliable. In his Tafsir of this Ayah, Al-Bukhari recorded that Al-`Awwam said that he asked Mujahid about the prostration in Surah Sad. He said, `I asked Ibn `Abbas, may Allah be pleased with him, `Why do you prostrate' He said, `Have you not read:
وَمِن ذُرِّيَّتِهِ دَاوُودَ وَسُلَيْمَـنَ
(and among his Nuh's progeny Dawud, Sulayman) (6:84)
أُوْلَـئِكَ الَّذِينَ هَدَى اللَّهُ فَبِهُدَاهُمُ اقْتَدِهْ
(They are those whom Allah had guided. So follow their guidance) (6:90). Dawud, peace be upon him, was one of those whom your Prophet was commanded to follow. Dawud prostrated here so the Messenger of Allah ﷺ also prostrated here."' Abu Dawud recorded that Abu Sa`id Al-Khudri, may Allah be pleased with him, said, "The Messenger of Allah ﷺ recited Sad while he was on the Minbar. When he reached the prostration, he came down from the Minbar and prostrated, and the people prostrated with him. On another occasion when he recited it, he reached the prostration and the people prepared to prostrate. He said:
«إِنَّمَا هِيَ تَوْبَةُ نَبِيَ، وَلَكِنِّي رَأَيْتُكُمْ تَشَزَّنْتُم»
(This is repentance for a Prophet, but I see that you are preparing to prostrate.) Then he came down (from the Minbar) and prostrated." This was recorded only by Abu Dawud and its chain of narration meets the conditions of the Two Sahihs.
وَإِنَّ لَهُ عِندَنَا لَزُلْفَى وَحُسْنَ مَـَابٍ
(and verily, for him is a near access to Us, and a good place of (final) return.) means, on the Day of Resurrection, he will have good deeds by virtue of which he will be brought close to Allah, and he will have a good place of (final) return, which means the lofty levels of Paradise, because of his repentance and his perfect justice in his kingdom. As it says in the Sahih:
«الْمُقْسِطُونَ عَلَى مَنَابِرَ مِنْ نُورٍ عَنْ يَمِينِ الرَّحْمنِ، وَكِلْتَا يَدَيْهِ يَمِينٌ، الَّذِينَ يُقْسِطُونَ فِي أَهْلِيهِمْ وَمَا وَلُوا»
(Those who are fair and just with their families and those who are under their authority will be on Minbars of light on the right hand of Ar-Rahman, and both His Hands are right Hands.)"