The sunan prayers and their virtues - Section 3 Mishkat al-Masabih 1183
Arabic hadith text
وَعَنِ ابْنِ عَبَّاسٍ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُطِيلُ الْقِرَاءَةَ فِي الرَّكْعَتَيْنِ بَعْدَ الْمَغْرِبِ حَتَّى يَتَفَرَّقَ أَهْلُ الْمَسْجِدِ. رَوَاهُ أَبُو دَاوُد
Translation
Ibn ‘Abbas said that God’s Messenger prolonged the recitation of the Qur’an in the two rak'as after the sunset prayer till the people in the mosque separated. Abu Dawud transmitted it.