Narrated Ubayy ibn Ka'b:
The Prophet (ﷺ) read the Qur'anic verse: "Thou hast received (full) excuse from me (min ladunni)" and put tashdid (doubling of consonants) on nun (n).
Narrated Ibn 'Abbas:
from 'Ubayy bin Ka'b, that the Prophet (ﷺ) would recite: "Qad Balaghta Min Ladunni 'Udhra" (18:76) with heaviness (Muthaqqalah - meaning with Tashdid on the Nun in "Ladunni")."