Qays bin Abbad reported,
While I was in the mosque standing in the front row, a man pulled me sharply from behind, moved me aside, and took my place. By Allah, I could not focus on my prayer.When the prayer ended, I saw that it was Ubayy bin Kaab. He said, "Young man, may Allah not bring you any harm. This is a covenant from the Prophet ﷺ to us, that we should stand directly behind him."Then he turned toward the qiblah and said, "The people of the knot are ruined, by the Lord of the Kaabah," repeating it three times. Then he said, "By Allah, I do not grieve for them, but I grieve for those they have led astray."I asked, "Abu Yaqub, who does he mean by the people of the knot?"He replied, "The rulers."
Azami 2298
Sahihعن قيس بن عباد قال
بينا أنا في المسجد في الصف المقدم فجبذني رجل من خلفي جبدة، فنحاني، وقام مقامي. فوالله ما عقلت صلاتي. فلما انصرف فإذا هو أبي بن كعب، فقال: يا فتى لا يسؤك الله: إن هذا عهد من النبي الله ﷺ إلينا أن نليه، ثم استقبل القبلة، فقال: هلك أهل العقد ورب الكعبة ثلاثا ثم قال: والله ما عليهم آسى، ولكن آسى على من أضلوا. قلت: يا أبا يعقوب! ما يعني بأهل العقدة؟ قال: الأمراء.
Nasai (808) narrated it, he said, Muhammad bin Umar bin Ali bin Muqaddam informed us, Yusuf bin Yaqub related to us, he said, Taymi informed me, from Abu Majliz, from Qays bin Abbad, and he related the hadith. Its chain is sahih. Abu Yaqub is Yusuf bin Yaqub, and the questioner is Muhammad bin Umar bin Ali bin Muqaddam. Taymi is Sulayman bin Tarkhan Taymi, one of the men accepted by all the compilers.Hakim narrated it in Mustadrak (1/214-215), and Ibn Khuzayma (1573), both through the route of Muhammad bin Umar Muqaddami. Hakim said, "Sahih according to the criterion of Bukhari, for he relied on Yusuf bin Yaqub Sadusi as evidence, though the two of them did not narrate it."Imam Ahmad narrated it (21264) in a lengthy context, from Muhammad bin Jafar, Shuba related to us, he said, I heard Abu Jamra, Iyas bin Qatada related to us, from Qays, meaning bin Abbad. Muhammad bin Jafar said, I dropped it from my book, it is from Qays, Allah willing.Sulayman bin Dawud and Wahb bin Jareer related to us, they said, Shuba related to us, from Abu Jamra, he said, I heard Iyas bin Qatada relating from Qays bin Abbad, he said, I came to Madinah to meet the companions of Muhammad 
, and there was no man among them whom I would have preferred to meet more than my father. Then the prayer was called. Umar came out with the companions of the Messenger of Allah , and I stood in the first row. A man came and looked at the faces of the people, and he recognized all of them except me, so he moved me aside and stood in my place. I lost track of my prayer because of this. When he finished praying, he said, "My son, may Allah not grieve you. What I did to you was not out of ignorance, but the Messenger of Allah said, 'Stand in the first row, the one nearest to me.' I looked at the faces of the people and I recognized all of them except you."Then he spoke further, and I have never seen men stretch their necks toward anything the way they stretched them toward what he said. He said, I heard him say, "The people of the knot have perished, by the Lord of the Kaaba. It is not for them that I grieve, but I grieve for the Muslims who will perish because of them." It turned out that he was my father.The wording of the hadith follows that of Sulayman bin Dawud, who is Abu Dawud Tayalisi, and he narrated it in his Musnad (557) through this same route. He said, the people of the knot are those who shed blood over it, seized it by force, and then held fast to it. Its chain is sahih. His words "stretch" mean they extended their necks toward him.Abdul-Razzaq narrated it (53/2) from Muhammad bin Rashid, from Khalid, from Qays bin Abbad. In it, Ubayy bin Kaab said, "I only held you back because the Messenger of Allah commanded us that the first row should be for the migrants and the helpers to pray in, and I realized that you were not one of them, so I held you back." I said, "Who is this?" They said, "Ubayy bin Kaab."