(19) باب ذِكْرِ ابْنِ صَيَّادٍ
'Muhammad b. Munkadir reported:
As I saw Jabir b. 'Abdullah taking an oath in the name of Allah that it was Ibn Sa'id who was the Dajjal I said: Do you take an oath in the name of Allah? Thereupon he said: I heard 'Umar taking an oath in the presence of Allah's Apostle (ﷺ) to this effect but Allah's Apostle (ﷺ) did not disapprove of it.
Reference: Sahih Muslim 2929
In-book reference: Book 54, Hadith 119
USC-MSA web (English) reference(deprecated numbering scheme): Book 41, Hadith 6999