Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
ahmad:542ʿAbdullāh > Surayj b. Yūnus

I offered the Eid prayer behind ʿUthman ؓ and he said the takbeer seven times and five times (i.e., in the first and second rak’ahs, respectively).  

أحمد:٥٤٢حَدَّثَنَا عَبْدُ اللهِ حَدَّثَنِي سُرَيْجُ بْنُ يُونُسَ حَدَّثَنَا مَحْبُوبُ بْنُ مُحْرِزٍ بَيَّاعُ الْقَوَارِيرِ كُوفِيٌّ ثِقَةٌ كَذَا قَالَ سُرَيْجٌ عَنْ إِبْرَاهِيمَ بْنِ عَبْدِ اللهِ يَعْنِي ابْنَ فَرُّوخَ عَنْ أَبِيهِ قَالَ

صَلَّيْتُ خَلْفَ عُثْمَانَ الْعِيدَ فَكَبَّرَ سَبْعًا وَخَمْسًا