Reading the Holy Quran with Elocution an...
Al-Kāfi
Volume 2, Book 3, Chapter 9
1ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ عَلِيِّ بْنِ مَعْبَدٍ عَنْ وَاصِلِ بْنِ سُلَيْمَانَ عَنْ عَبْدِ الله بْنِ سُلَيْمَانَ قَالَ
سَأَلْتُ أَبَا عَبْدِ الله (عَلَيهِ السَّلام) عَنْ قَوْلِ الله عَزَّ وَجَلَّ وَرَتِّلِ الْقُرْآنَ تَرْتِيلاً قَالَ قَالَ أَمِيرُ الْمُؤْمِنِينَ (صَلَّى اللهُ عَلَيْهِ وآلِه) بَيِّنْهُ تِبْيَاناً وَلا تَهُذَّهُ هَذَّ الشِّعْرِ وَلا تَنْثُرْهُ نَثْرَ الرَّمْلِ وَلَكِنْ أَفْزِعُوا قُلُوبَكُمُ الْقَاسِيَةَ وَلا يَكُنْ هَمُّ أَحَدِكُمْ آخِرَ السُّورَةِ.
1. Ali ibn Ibrahim has narrated from his father from Ali ibn Ma’bad from Wasil ibn Sulayman who has said the following:
“Once I asked Abu ‘Abdillah 
about the words of Allah, the Most Majestic, the Most Holy, ‘Read the Holy Quran in a distinct elocution (tartil ). . . .’ (73:4)<br/>The Imam said: ‘Amir al-Mu’minin, Ali ibn Abu Talib has said, 'It is to pronounce clearly and distinctively. Do not rush it like poems or scatter like pebbles but shake up your hard hearts thereby instead of your rushing to finish the chapter.'"
- مجهولMirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (12/499)Allamah Baqir al-Majlisi
