Musnad Ahmad 652:93

Isma'il narrated to us, from Yunus, from al-Hasan, that al-Nu'man ibn Bashir wrote to Qays ibn al-Haytham: "You are our brothers and our kin. We witnessed [events] while you did not witness them, and we heard [things] while you did not hear them. Indeed, the Messenger of Allah (peace and blessings of Allah be upon him) used to say: 'Between the hands of the Hour, there will be tribulations like pieces of the dark night. A man will wake up in them as a believer and go to sleep as a disbeliever, and in them, people will sell their share [of the Hereafter] for a small portion of the worldly life.'"