Sahih Muslim Book 4, Hadith Number 1798.

Chapter : Reciting the Qur’an leisurely and distinctively and abstaining from reciting it too hurriedly, and permission to recite two suras of more than two in a Rak’ah.

Ishaq is reported to have said on the authority of Aswad who quoted on the authority of ‘Abdullah b. Mas’ud that the Apostle of Allah (may peace be upon him) used to recite these words as (fahal min muddakir).