Sunan an-Nasa'i 1274

أَخْبَرَنِي أَحْمَدُ بْنُ يَحْيَى الصُّوفِيُّ، قَالَ حَدَّثَنَا أَبُو نُعَيْمٍ، قَالَ حَدَّثَنَا عِصَامُ بْنُ قُدَامَةَ الْجَدَلِيُّ، قَالَ حَدَّثَنِي مَالِكُ بْنُ نُمَيْرٍ الْخُزَاعِيُّ، مِنْ أَهْلِ الْبَصْرَةِ أَنَّ أَبَاهُ، حَدَّثَهُ أَنَّهُ، رَأَى رَسُولَ اللَّهِ صلى الله عليه وسلم قَاعِدًا فِي الصَّلاَةِ وَاضِعًا ذِرَاعَهُ الْيُمْنَى عَلَى فَخِذِهِ الْيُمْنَى رَافِعًا أُصْبُعَهُ السَّبَّابَةَ قَدْ أَحْنَاهَا شَيْئًا وَهُوَ يَدْعُو ‏.‏

Malik bin Numair Al-Khuza'I, one of the inhabitants of Al-Basrah, narrated that:His father told him that he saw the Messenger of Allah (ﷺ) sitting when praying, putting his right forearm on his right thigh and raising his forefinger, which he had bent slightly, and he was supplicating

Reference

Sunan an-Nasa'i 1274

In-book

Book 13, Hadith 96