Abu Dawud said: Ibn-Zubair made two prostrations before giving the salutation in a similar way when he stood up at the end of two rak'ahs. This is the opinion of al-Zuhri.
In-book : Book 2, Hadith 646
English translation : Book 2, Hadith 1030
2. Prayer (Kitab Al-Salat)
باب مَنْ قَامَ مِنْ ثِنْتَيْنِ وَلَمْ يَتَشَهَّدْ