Sunan an-Nasa'i, Volume 2, Book 11, Hadith 888 (DarusSalam) ⓘ

It was narrated that Musa bin Umair Al-Anbari and Qais bin Sulaim Al-Anbari said: "Alqamah bin Wa'il told us that his father said: "I saw the Messenger of Allah, when he was standing in prayer, holding his left hand with his right.'"

أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ مُوسَى بْنِ عُمَيْرٍ الْعَنْبَرِيِّ، وَقَيْسِ بْنِ سُلَيْمٍ الْعَنْبَرِيِّ، قَالاَ حَدَّثَنَا عَلْقَمَةُ بْنُ وَائِلٍ، عَنْ أَبِيهِ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم إِذَا كَانَ قَائِمًا فِي الصَّلاَةِ قَبَضَ بِيَمِينِهِ عَلَى شِمَالِهِ ‏.‏