Ubaydullah bin Abdullah bin Utbah (may Allah have mercy on him) narrates: Sayyiduna Ibn Abbas (may Allah be pleased with them both) said to me: "O Ibn Utbah! Do you know which is the last surah of the Qur'an that was revealed complete (all at once)?" I said: "Yes, it is 'When the help of Allah comes'." He said: "You have spoken the truth."
No one narrated this hadith from Ubaydullah bin Abdullah except Abd al-Majid bin Suhayl, and no one from Abd al-Majid except Abu al-Umays; Ja'far bin Awn is alone in narrating it.
Hadith Referenceالمعجم الأوسط / باب الميم / 7263
Hadith Takhrij«أخرجه مسلم فى «صحيحه» برقم: 3024، والنسائي فى «السنن الكبرى» برقم: 11649، وابن أبي شيبة فى «مصنفه» برقم: 37033، والطبراني فى «الكبير» برقم: 10736»