Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:73:4 –

Or add to it, and recite the Qur'an with measured recitation.  

or add to it, up to two thirds (aw implies ˹free˺ choice), and recite the Qur’ān, recite it carefully, in a measured tone.
القرآن:٧٣:٤ –

أَوْ زِدْ عَلَيْهِ وَرَتِّلِ الْقُرْآنَ تَرْتِيلًا  

{أو زد عليه} إلى الثلثين وأو للتخيير {ورتل القرآن} تثبت في تلاوته {ترتيلا}.