Sahih al Bukhari 1220
Actions while Praying
حَدَّثَنَا عَمْرُو بْنُ عَلِيٍّ، حَدَّثَنَا يَحْيَى، حَدَّثَنَا هِشَامٌ، حَدَّثَنَا مُحَمَّدٌ، عَنْ أَبِي هُرَيْرَةَ، رضى الله عنه قَالَ نُهِيَ أَنْ يُصَلِّيَ الرَّجُلُ مُخْتَصِرًا.
Narrated Abu Huraira:It was forbidden to pray with the hands over one's hips
Text from the public-domain hadith-api dataset. Numbering follows that dataset and can differ by a few from some printed editions — check the wording, not only the number.