Hadithcore
Mishkat al-Masabih, 1317

Mu'adh b. Anas al-Juhani reported God’s Messenger as saying, “If anyone sits in his place of prayer when he finishes the Morning Prayer till he prays the two <i>rak'as</i> of the forenoon, saying nothing but what is good, his sins will be forgiven him even if they are more than the foam of the sea.” Abu Dawud transmitted it.

وَعَن معَاذ بن أنس الْجُهَنِيِّ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ قَعَدَ فِي مُصَلَّاهُ حِينَ يَنْصَرِفُ مِنْ صَلَاةِ الصُّبْحِ حَتَّى يُسَبِّحَ رَكْعَتَيِ الضُّحَى لَا يَقُولُ إِلَّا خَيْرًا غُفِرَ لَهُ خَطَايَاهُ وَإِنْ كَانَتْ أَكْثَرَ مِنْ زَبَدِ الْبَحْرِ» . رَوَاهُ أَبُو دَاوُد

References1 variant
In-Book Reference
Book 4, Hadith 726