Hadith 576
It is narrated from Wasih bin Hayan that he asked Sayyiduna Ibn Umar (may Allah be pleased with them both) about the prayer of the Messenger of Allah (peace and blessings be upon him), so he said, "Whenever the Prophet (peace and blessings be upon him) would stand up or bow down, he would say « اللهُ أَكْبَرُ »." And he added, "Then the Prophet (peace and blessings be upon him) would say « السَّلَامُ عَلَيْكُمْ وَرَحْمَةُ اللَّهِ » to his right side and « السَّلَامُ عَلَيْكُمْ وَرَحْمَةُ اللَّهِ » to his left side as well." Imam Abu Bakr (may Allah have mercy on him) says that the students of Amr bin Yahya have differed in this chain; they say that they asked Abdullah bin Zaid bin Asim. I have mentioned this in Kitab al-Kabir.
Hadith 577
Hazrat Ikrimah narrates that I saw a man near Maqam Ibrahim (during prayer) saying takbeer at every rising and bowing, so I went to Sayyiduna Ibn Abbas (may Allah be pleased with them both) and said, "I saw a man praying who says « اللهُ أَكْبَرُ » at every rising and bowing?" He replied, "May your mother die! Is this not the prayer of the Messenger of Allah (peace and blessings be upon him)?"