The Prophet ﷺ said, "The great battle, the conquest of Constantinople, and the emergence of Dajjal will all occur within seven months."
حدثنا عبد الله بن عبد الرحمن أخبرنا الحكم بن المبارك حدثنا الوليد بن مسلم عن أبي بكر بن أبي مريم عن الوليد بن سفيان عن يزيد بن قطيب السكوني عن أبي بحرية صاحب معاذ
عن النبي ﷺ قال الملحمة العظمى وفتح القسطنطينية وخروج الدجال في سبعة أشهر
[Its chain is daif] Ibn Majah also reported it in "Fitan," chapter on "Malahim," no. 4092, from the hadith of Walid, and Abu Dawud, no. 4295, from the hadith of Abu Bakr bin Abu Maryam through him, and he is well known to be daif, while Walid bin Sufyan and Yazid Sakuni are both majhul.On this topic there is also a narration from Saab bin Jathama [Abdullah bin Ahmad in "Zawaid al-Musnad," 4/71, 72], from Abdullah bin Busr [Abu Dawud, no. 4296], from Abdullah bin Masud [he perhaps means the hadith in Muslim, no. 2899], and from Abu Saeed Khudri [he perhaps means the hadith in Muslim, no. 2938].