Hadithcore
Mishkat al-Masabih, 1318

Abu Huraira reported God’s Messenger as saying, “If anyone perseveres in praying the two <i>rak'as</i> of the forenoon, his sins will be forgiven him, even if they are like the foam of the sea.” Ahmad, Tirmidhi and Ibn Majah transmitted it.

وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ حَافَظَ عَلَى شُفْعَةِ الضُّحَى غُفِرَتْ لَهُ ذنُوبه وَإِن كَانَت مثلا زَبَدِ الْبَحْرِ» . رَوَاهُ أَحْمَدُ وَالتِّرْمِذِيُّ وَابْنُ مَاجَهْ

References1 variant
In-Book Reference
Book 4, Hadith 727