Sunan At-Tirmidhi

Hadith #2933

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)