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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 rak'as 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.
Source: sunnah.com
Other translations
Arabic
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
sunnah.com