Narrated Anas (RA):

Allah's Messenger (ﷺ) said: "Whoever prays twelve Rak'at of Duha, Allah will build a castle for him in Paradise." [Reported by at-Tirmidhi who graded it Gharib (reported by a single narrator)].

وَعَنْ أَنَسٍ قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ مَنْ صَلَّى اَلضُّحَى ثِنْتَيْ عَشْرَةَ رَكْعَةً بَنَى اَللَّهُ لَهُ قَصْرًا فِي اَلْجَنَّةِ } رَوَاهُ اَلتِّرْمِذِيُّ وَاسْتَغْرَبَهُ .‏ [1]‏ .‏