Musannaf Ibn Abi Shayba 37:100

Abu Usama narrated to us, he said: Abd al-Rahman ibn Yazid ibn Jabir narrated to us, from Makhul, he said: There is nothing between the Great Battle (al-Malhama), the conquest of Constantinople, and the emergence of the Dajjal except seven months. And that is not but like the likeness of a necklace that is severed, so some of it follows the other.