"My father told me: 'I prayed behind the Messenger of Allah ﷺ and I saw him raise his hands when he started to pray, and when he bowed, and when he said: Sami' Allahu liman hamidah (Allah hears the one who praises Him)" like this.'" And (one of the narrators) Qais pointed towards his ears. (Using translation from Nasāʾī 1055)  

صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ فَرَأَيْتُهُ يَرْفَعُ يَدَيْهِ إِذَا افْتَتَحَ الصَّلَاةَ وَإِذَا رَكَعَ وَإِذَا قَالَ «سَمِعَ اللهُ لِمَنْ حَمِدَهُ» هَكَذَا فَأَشَارَ قَيْسٌ إِلَى نَحْوِ الْأُذُنَيْنِ