Hadith #3994 (Sunan Abi Dawud)
Book: Dialects and Readings of the Qur'an (Kitab Al-Huruf Wa Al-Qira'at)
Narrator(s): Abdul Malik bin Abd عبد الملك بن عبد الرحمن, Ahmed bin Salah al-Masri أحمد بن صالح المصري, Jabir ibn 'Abdullah, Muhammad bin al-Munkdar bin 'Abdullah محمد بن المنكدر بن عبد الله بن الهدير, Sufyan bin Sa‘id Ath-Thawri سفيان الثوري
Grade: Sahih

The Prophet (ﷺ) used to read the verse “Is there any that will receive admonition (muddakir)? ” that is with doubling of consonant .
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.

Source: https://parallelquran.com/hadith/sunan-abi-dawud-3994/