Sahih Bukhari Volume 6, Book 60, Hadith Number 394.

Narrated By Abu Ishaq : A man asked Al-Aswad, ‘is it ‘Fahal min-Muddakir’ or ‘…Mudhdhakir?” Al Aswad replied, ‘I have heard Abdullah bin Masud reciting it, ‘Fahal-min Muddakir’; I too, heard the Prophet reciting it ‘Fahal-min-Muddakir’ with ‘d’.