Sunan an-Nasa'i 1162

أَخْبَرَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ الدَّوْرَقِيُّ، عَنِ الأَشْجَعِيِّ، عَنْ سُفْيَانَ، عَنْ أَبِي إِسْحَاقَ، عَنِ الأَسْوَدِ، عَنْ عَبْدِ اللَّهِ، قَالَ عَلَّمَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم أَنْ نَقُولَ إِذَا جَلَسْنَا فِي الرَّكْعَتَيْنِ ‏ "‏ التَّحِيَّاتُ لِلَّهِ وَالصَّلَوَاتُ وَالطَّيِّبَاتُ السَّلاَمُ عَلَيْكَ أَيُّهَا النَّبِيُّ وَرَحْمَةُ اللَّهِ وَبَرَكَاتُهُ السَّلاَمُ عَلَيْنَا وَعَلَى عِبَادِ اللَّهِ الصَّالِحِينَ أَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ ‏"‏ ‏.‏

It was narrated that 'Abdullah said:"The Messenger of Allah (ﷺ) taught us to say when we sat following two rak'ahs: 'At-tahiyyatu lillahi was-salawatu wat-tayyibat, as-salamu 'alaika ayyuhan-Nabiyyu wa rahmatAllahi wa baraktuhu. As-salamu 'alaina wa 'ala 'ibad illahis-salihin, ashahdu an la illaha ill-Allah wa ashhadu anna Muhammadan 'abduhu wa rasuluhu (Allah compliments, prayers and pure words are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah (SWT) and his blessings. Peace be upon us and upon the righteous slaves of Allah (SWT). I bear witness that none has the right to be worshipped except Allah and I bear witness that Muhammad is His slave and Messenger

Reference

Sunan an-Nasa'i 1162

In-book

Book 12, Hadith 134