Musannaf Ibn Abi Shayba 33:1043

Qutaybah ibn Sa'id narrated to us, he said: Ibrahim narrated to us, from Abu Sahl, from al-Hasan, regarding His saying: "Indeed, Hell has been a place of ambush" (78:21). He said: "It lies in wait for them, by Allah." He said: "And while a man was passing, another met him and said: 'Has it reached you that there is an ambush on the road?' He said: 'Then take your precaution.'"