When we said prayer with the Messenger of Allah ﷺ, we pronounced: Peace be upon you and Mercy of Allah, peace be upon you and Mercy of Allah, and made gesture with the hand on both the sides. Upon this the Messenger of Allah (may peace be upon him said: What do you point out with your hands as if they are the tails of headstrong horses? This is enough for you that one should place one's hand on one's thigh and then pronounce salutation upon one's brother on the right side and then on the left. (Using translation from Muslim 431a)   

كُنَّا إِذَا صَلَّيْنَا خَلْفَ النَّبِيَّ ﷺ قُلْنَا السَّلَامُ عَلَيْكُمُ السَّلَامُ عَلَيْكُمْ وَأَشَارَ مِسْعَرٌ بِيَدِهِ عَنْ يَمِينِهِ وَعَنْ شِمَالِهِ فَقَالَ «مَا بَالُ هَؤُلَاءِ الَّذِينَ يُومِئُونَ بِأَيْدِيهِمْ كَأَنَّهَا أَذْنَابُ الْخَيْلِ الشُّمْسِ أَمَا يَكْفِي أَحَدُهُمْ أَنْ يَضَعَ يَدَهُ عَلَى فَخِذِهِ ثُمَّ يُسَلِّمَ عَلَى أَخِيهِ عَنْ يَمِينِهِ وَشِمَالِهِ»