The Prophet ﷺ prostrated in Sad and said: "Dawud did this prostration in repentance and we do it in thanksgiving." (Using translation from Nasāʾī 957)
أَنَّ النَّبِيَّ ﷺ سَجَدَ فِي ص وَقَالَ «سَجَدَهَا دَاوُدُ عَلَيْهِ السَّلَامُ تَوْبَةً وَنَسْجُدُهَا شُكْرًا»