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 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 also prostrated here.''' Abu Dawud recorded that Abu Sa`id Al-Khudri, may Allah be pleased with him, said, "The Messenger of Allah 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.)''

﴿يدَاوُودُ إِنَّا جَعَلْنَـكَ خَلِيفَةً فِى الاٌّرْضِ فَاحْكُمْ بَيْنَ النَّاسِ بِالْحَقِّ وَلاَ تَتَّبِعِ الْهَوَى فَيُضِلَّكَ عَن سَبِيلِ اللَّهِ إِنَّ الَّذِينَ يَضِلُّونَ عَن سَبِيلِ اللَّهِ لَهُمْ عَذَابٌ شَدِيدُ بِمَا نَسُواْ يَوْمَ الْحِسَابِ ﴾

(26. O Dawud! Verily, We have placed you as a successor on the earth; so judge you between men in truth (and justice) and follow not your desire -- for it will mislead you from the path of Allah. Verily, those who wander astray from the path of Allah (shall) have a severe torment, because they forgot the Day of Reckoning.)