Abdullah bin Amr bin As reported,
A man came to him and said, "What is this hadith you are narrating? You say that the Hour will come at such and such a time?"He replied, "Subhan Allah," or "La ilaha illa Allah," or some words to that effect. "I have a mind never to narrate anything to anyone again. All I said was that you will soon witness a tremendous matter. The House will be burned, and such and such will happen."Then he said, the Messenger of Allah ﷺ said, "Dajjal will appear in my nation and will remain for forty. I do not know whether it is forty days, forty months, or forty years. Then Allah will send Isa, son of Maryam, who resembles Urwa bin Masud. He will pursue him and destroy him." …the rest of the hadith.
Azami 709
Sahihعن عبد الله بن عمرو بن العاص
وجاءه رجل فقال: ما هذا الحديث الذي تحدث به؟ تقول: إن الساعة تقوم إلى كذا وكذا؟ فقال: سبحان الله! أو لا إله إلا الله أو كلمة نحوهما، لقد هممت أن لا أحدث أحدا شيئا أبدا إنما قلت: إنكم سترون بعد قليل أمرا عظيما: يحرق البيت ويكون ثم قال: قال رسول الله ﷺ: يخرج الدجال في أمتي فيمكث أربعين لا أدري أربعين يوما أو أربعين شهرا أو أربعين عاما، فيبعث الله عيسى ابن مريم كاته عروة بن مسعود فيطلبه فيهلكه… الحديث.
and his killing of Dajjal and his killing of DajjalMuslim narrated it in Fitan (2940) from Ubaydullah bin Muaz Anbari, who said, my father told us, Shuba told us, from Numan bin Salim, who said, I heard Yaqub bin Asim bin Urwa bin Masud Thaqafi say, I heard Abdullah bin Amr say, and a man came, then he mentioned it in a long hadith.As for his statement, "I do not know whether it is forty days, forty months, or forty years," this hesitation comes from Abdullah bin Amr himself. Perhaps he did not precisely retain from the Prophet ﷺ the detailed account found in the hadith of Nawas bin Saman, as mentioned earlier. It is also possible that the Prophet sometimes said simply "forty" without elaborating, and at other times specified the detail.