I prayed beside Abdullah bin Umar. When he finished the prayer, he struck his hand on his thigh and said, "Shall I not teach you the greeting of the prayer just as the Messenger of Allah ﷺ used to teach us?" Then he recited to me these words, meaning the wording of Abu Musa Ashari regarding the tashahhud.
حدثنا عفان حدثنا أبان بن يزيد حدثنا قتادة
صليت إلى جنب عبد الله بن عمر قال فلما قضى الصلاة ضرب بيده على فخذه فقال ألا أعلمك تحية الصلاة كما كان رسول الله ﷺ يعلمنا فتلا علي هؤلاء الكلمات يعني قول أبي موسى الأشعري في التشهد
Its chain of transmission is sahih. Abu Aban bin Yazid Attar, his reliability was established previously at 1502, and we add here that Ibn Main, Ibn Madini, Nasai and others also confirmed him as reliable, and Ahmad said, "He is firmly established among all the teachers," and Bukhari gave his biography in Kabir 1/1/454.Abdullah bin Babi, his reliability was established previously at 174, where his father's name was given as Babih, though there is a third reading, Babah. Ibn Madini said, "He is known among the people of Makkah," and Ibn Madini, Nasai, Ajli and others confirmed him as reliable. Ibn Main claimed that they were three different men, based on the differing accounts of his father's name. Husayn bin Bara said, "In my view, the correct position is what Ibn Madini and Bukhari said," meaning that he is one and the same man, and these are simply close variant narrations regarding his father's name.He did not give the wording of the tashahhud here, but instead referred to the hadith of Abu Musa Ashari, which will come in the Musnad of Abu Musa at 4:409 H. It was also narrated from the hadith of Abu Musa by Muslim, Abu Dawud, Nasai and Ibn Majah, as mentioned in Nasb Raya 1:421.Abu Dawud narrated the tashahhud from the hadith of Ibn Umar at 1:367, by way of Shubah, from Abu Bishr, "I heard Mujahid narrating from Ibn Umar, from the Messenger of Allah ﷺ," regarding the tashahhud, "All greetings belong to Allah, and all good prayers, peace be upon you, O Prophet, and the mercy of Allah and His blessings." He said, Ibn Umar said, "I added to it, 'and His blessings, peace be upon us and upon the righteous servants of Allah, I bear witness that there is no god but Allah.'" Ibn Umar said, "I added to it, 'alone, with no partner, and I bear witness that Muhammad is His servant and His messenger.'"This chain of transmission is sahih, and Abu Bishr is Jafar bin Abu Wahshiya. It was likewise narrated by Daraqutni at 134, by way of Shubah. It was likewise narrated by Bayhaqi at 2:139, by way of Abu Dawud and others, from the hadith of Shubah, after which he said, "It has also been narrated from Abdullah bin Babi, from Ibn Umar, from the Prophet ﷺ." I found no reference to this narration except the one made by Bayhaqi.