Musannaf Ibn Abi Shayba 3:3578

Waki’ narrated to us, from Muhammad ibn Qays, from Ibn ‘Awn al-Thaqafi, that al-Hasan ibn ‘Ali used to pray four [rak’ahs] before the Dhuhr [prayer], making them long. Ibn ‘Awn said: If he was light in his recitation, then [he would recite] from the *Tiwal* (long surahs), and if he was slow in his recitation, then [he would recite] from the *Mi’in* (surahs of approximately one hundred verses).