مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 1038
Prayer
Prostration while Reciting the Qur’an - Section 3
وَعَنِ ابْنِ عَبَّاسٍ قَالَ: إِنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ سَجَدَ فِي (ص) وَقَالَ: سَجَدَهَا دَاوُدُ تَوْبَةً وَنَسْجُدُهَا شُكْرًا. رَوَاهُ النَّسَائِيُّ
Ibn ‘Abbas said that the Prophet (ﷺ) prostrated himself when reciting Sad (Al-Qur’an; 38) and said, "David made this prostration in repentance, but we do it out of gratitude.” Nasa’i transmitted it.
Mishkat al-Masabih, 1038صَحِيح (الألباني)