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")." (JA)
English reference (JA): Vol. 5, Book 43, Hadith 2933 (JA)
Arabic reference (JA): Book 46, Hadith 3184 (JA)