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.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
nasai-kubra:1773 – Isḥāq b. Manṣūr > ʿAbd al-Raḥman > Sufyān > al-Ashʿath > al-Aswad b. Hilāl > Thaʿlabah b. Zahdam

'Ali appointed Abu Mas'ud over the people, then went out on the day of 'Eid and said: 'O people, it is not part of the sunnah to pray before the imam.'" (Using translation from Nasāʾī 1561)  

الكبرى للنسائي:١٧٧٣ – أَخْبَرَنَا إِسْحَاقُ بْنُ مَنْصُورٍ قَالَ أَخْبَرَنَا عَبْدُ الرَّحْمَنِ عَنْ سُفْيَانَ عَنِ الْأَشْعَثِ عَنِ الْأَسْوَدِ بْنِ هِلَالٍ عَنْ ثَعْلَبَةَ بْنِ زَهْدَمٍ

أَنَّ عَلِيًّا اسْتَخْلَفَ أَبَا مَسْعُودٍ عَلَى النَّاسِ فَخَرَجَ يَوْمَ عِيدٍ فَقَالَ «يَا أَيُّهَا النَّاسُ إِنَّهُ لَيْسَ مِنَ السُّنَّةِ أَنْ يُصَلَّى قَبْلَ الْإِمَامِ»  

See similar narrations below:

Collected by Nasāʾī
nasai:1561 – Isḥāq b. Manṣūr > ʿAbd al-Raḥman > Sufyān > al-Ashʿath > al-Aswad b. Hilāl > Thaʿlabah b. Zahdam

'Ali appointed Abu Mas'ud over the people, then went out on the day of 'Eid and said: 'O people, it is not part of the sunnah to pray before the imam.'"  

النسائي:١٥٦١ – أَخْبَرَنَا إِسْحَاقُ بْنُ مَنْصُورٍ قَالَ أَنْبَأَنَا عَبْدُ الرَّحْمَنِ عَنْ سُفْيَانَ عَنِ الأَشْعَثِ عَنِ الأَسْوَدِ بْنِ هِلاَلٍ عَنْ ثَعْلَبَةَ بْنِ زَهْدَمٍ

أَنَّ عَلِيًّا اسْتَخْلَفَ أَبَا مَسْعُودٍ عَلَى النَّاسِ فَخَرَجَ يَوْمَ عِيدٍ فَقَالَ يَا أَيُّهَا النَّاسُ إِنَّهُ لَيْسَ مِنَ السُّنَّةِ أَنْ يُصَلَّى قَبْلَ الإِمَامِ