From Sahih Bukhari (Hadith 4430):
Narrated Ibn `Abbas: `Umar bin Al-Khattab used to let Ibn `Abbas sit beside him, so `AbdurRahman bin `Auf said to `Umar, "We have sons similar to him." `Umar replied, "(I respect him) because of his status that you know." `Umar then asked Ibn `Abbas about the meaning of this Holy Verse:-- "When comes the help of Allah and the conquest of Mecca . . ." (110.1) Ibn `Abbas replied, "That indicated the death of Allah's Messenger (ﷺ) which Allah informed him of." `Umar said, "I do not understand of it except what you understand
Reference: Bukhari 4430