Hadith 204

Bulugh al-Maram

Book 2: The Book of Prayer
وَلِلنَّسَائِيِّ : { كُنَّا نَقُولُ قَبْلِ أَنْ يُفْرَضَ عَلَيْنَا اَلتَّشَهُّدُ } .‏ 1‏
In the narration of an-Nasa'i:

'We used to say before at-Tashahhud become obligatory on us'.