Musannaf Ibn Abi Shayba 37:280

Affan narrated to us, he said: Abu 'Awanah narrated to us, he said: Ibrahim bin Muhammad bin al-Muntashir narrated to us, from his father, from Hudhayfah, who said: "When the people of al-Sham are cursed, then whoever among you is able to die, let him die."