[Machine] A man said to Ibn Mas'ood, "How do you know that this letter (ياس) is pronounced as 'yaasin' and not 'aasin'?" Ibn Mas'ood replied, "Have you read the entire Quran?" The man said, "I have recited the detailed recitation in one rakah (unit of prayer)." Ibn Mas'ood then asked, "Is this poem not from your father? I know the verses recited by the Messenger of Allah ﷺ , who used to pair two similar verses from the beginning of the Surah. And the first Surah in which Ibn Mas'ood used this pairing methodology was Surah Al-Rahman."  

أَنَّ رَجُلًا قَالَ لِابْنِ مَسْعُودٍ كَيْفَ تَعْرِفُ هَذَا الْحَرْفَ مَاءٌ غَيْرُ يَاسِنٍ أَمْ آسِنٍ؟ فَقَالَ كُلَّ الْقُرْآنِ قَدْ قَرَأْتَ؟ قَالَ إِنِّي لَأَقْرَأُ الْمُفَصَّلَ أَجْمَعَ فِي رَكْعَةٍ وَاحِدَةٍ فَقَالَ أَهَذَّ الشِّعْرِ لَا أَبَا لَكَ؟ قَدْ عَلِمْتُ قَرَائِنَ رَسُولِ اللهِ ﷺ الَّتِي كَانَ يَقْرُنُ قَرِينَتَيْنِ قَرِينَتَيْنِ مِنْ أَوَّلِ الْمُفَصَّلِ وَكَانَ أَوَّلُ مُفَصَّلِ ابْنِ مَسْعُودٍ (الرَّحْمَنُ)