Musnad Ahmad 31:214

Muhammad ibn Ja‘far narrated to us, ‘Uthman ibn Ghiyath narrated to us—and he dictated it to me—he said: I heard Abu Nadrah narrating from Abu Sa‘id al-Khudri, who said: The Messenger of Allah (may Allah bless him and grant him peace) mentioned the intercession and said: "Indeed, the people will be presented upon the bridge of Hell, and upon it will be thorns and hooks that snatch the people. On its sides will be the angels, saying: 'O Allah, grant safety, grant safety.'" Then he mentioned the rest of the hadith.