Abdullah bin Umar reported,
Umar addressed us at al-Jabiyah and said, "People, I stand among you as the Messenger of Allah ﷺ once stood among us, when he said, 'I urge you to honor my Companions, then those who follow them, then those who follow them. After that, lying will spread, until a man will swear an oath without being asked to, and a witness will give testimony without being called upon. Let no man be alone with a woman, for Satan is the third one present with them. Hold fast to the community and beware of division, for Satan is with the one who is alone, but he is farther from two. Whoever desires the heart of Paradise must cling to the community. Whoever is gladdened by his good deeds and grieved by his bad deeds, that is the true believer.'"
Azami 191
Sahihعن ابن عمر قال
خطبنا عمر بالجابية فقال: يا أيها الناس إني قمت فيكم كمقام رسول الله ﷺ فينا فقال: أوصيكم بأصحابي، ثم الذين يلونهم ثم الذين يلونهم ثم يفشو الكذب، حتى يحلف الرجل ولا يستحلف، ويشهد الشاهد ولا يستشهد، ألا لا يخلون رجل بامرأة إلا كان ثالثهما الشيطان، عليكم بالجماعة، وإياكم والفرقة، فإن الشيطان مع الواحد وهو من الاثنين أبعد، من أراد بحبوحة الجنة فليلزم الجماعة، من سرته حسنته وساءته سيئته فذلكم المؤمن.
Tirmidhi (2165) narrated it from Ahmad bin Mani, who said, Nadr bin Ismail Abu Mughira narrated to us, from Muhammad bin Suqa, from Abdullah bin Dinar, from Ibn Umar, and he related the hadith. Imam Ahmad (114) also narrated it, and Ibn Hibban (7254) and Hakim (1/113) graded it sahih, all of them through the route of Muhammad bin Suqa. Hakim said, "Sahih according to the criteria of the two Shaykhs." Tirmidhi said, "Hasan sahih gharib."On this same topic, from Abu Musa, who said, "I heard the Messenger of Allah ﷺ say, 'Whoever does a good deed and is pleased by it, and does a bad deed and is troubled by it, is a believer.'" This is disconnected. Imam Ahmad (19565) narrated it, as did Bazzar in Kashf Astar (79), and Hakim (1/13, 54), all of them from the hadith of Abdul-Aziz bin Muhammad, from Amr (meaning Ibn Abu Amr), from Muttalib, from Abu Musa, and he related the hadith. Muttalib is Ibn Abdullah bin Hantab, who is not known to have heard directly from any companion, as Tirmidhi relates in Ilal al-Kabir (2/964) from Bukhari.Hakim said, "The two of them relied on the narrators of this hadith down to the very last of them, and it is sahih according to their criteria, though they did not include it. They only included, in the sermon of Umar bin Khattab, 'Whoever is pleased by his good deed and troubled by his bad deed is a believer.'" End of quote. Dhahabi agreed that it meets their criteria.But the correct view is that it is not sahih, nor does it meet their criteria, because there is a break in its chain of transmission, and a disconnected hadith cannot be sahih, let alone meet their criteria.On this same topic also, from Amir bin Rabia, who said, the Messenger of Allah ﷺ said, "Whoever dies without having pledged obedience dies the death of ignorance. And whoever removes it after it has been bound around his neck will meet Allah 
with no argument in his defense. Beware, let no man be alone with a woman who is not lawful to him, for the third of them is Satan, unless she is a relative he is forbidden to marry, for Satan stays with the lone individual, and he keeps a greater distance from two. Whoever is troubled by his bad deed and pleased by his good deed is a believer."Husayn said, "after he has tied it around his neck." Its chain of transmission is daif. Imam Ahmad (15696) narrated it, and Bazzar in Kashf Astar (1636), both of them from the hadith of Sharik, from Asim bin Ubaydullah, from Abdullah bin Amir (meaning Ibn Rabia), from his father, and he related the hadith. Asim bin Ubaydullah is Ibn Asim bin Umar bin Khattab, and he is daif, which is why Haythami attributed the defect of this hadith to him in Majma (5/223–224).