Weak (da'if) — scholars do not use this report as evidence for rulings.
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)
Verses18:76