"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.  

صَلَّيْتُ خَلْفَ رَسُولِ اللَّهِ ﷺ فَرَأَيْتُهُ يَرْفَعُ يَدَيْهِ إِذَا افْتَتَحَ الصَّلاَةَ وَإِذَا رَكَعَ وَإِذَا قَالَ سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ هَكَذَا وَأَشَارَ قَيْسٌ إِلَى نَحْوِ الأُذُنَيْنِ