Sahih Muslim
The Book Giving Description of the Day of Judgement, Paradise and Hell (Kitab Sifat Al-Qiyamah wal Janna wan-Nar)
Book Number: 039 / Hadith Number: 6723
Ubayy b. Ka'b reported that the words of Allah, the Exalted and Glorious:" We will, surely, make them taste the lesser punishment before the severer punishment (that haply they may return)" (xxxii. 21) imply the torments of the world. (victory of) Rome, seizing (of the Meccans), or smoke. And Shalba was in doubt about seizing or smoke.