(1) باب
Narrated Abdullah ibn Mas'ud:
The Prophet (ﷺ) used to read the verse "Is there any that will receive admonition (muddakir)? " that is with doubling of consonant [(dal)(d)].Abu Dawud said: The word muddakir may be pronounced as mim (m) with a short vowel u. (dal)(d) with a short vowel and kaf (k) with a short vowel i.
Reference: Sunan Abi Dawud 3994
In-book reference: Book 32, Hadith 26
English translation: Book 31, Hadith 3983