"Anas bin Malik was asked about the takbir in the prayer. He said: "The takbir should be said when bowing, when prostrating, when raising one's head from prostration and when standing up following the first two rak'ahs.' Hutaim said: 'From whom did you learn this?' He said: 'From the Prophet ﷺ, Abu Bakr and 'Umar, may Allah (SWT) be pleased with them.' Then he fell silent and Hutaim said to him: 'And 'Uthman?' He said: 'And 'Uthman.'" (Using translation from Nasāʾī 1179)
«يُكَبِّرُ إِذَا رَكَعَ وَإِذَا سَجَدَ وَإِذَا رَفَعَ رَأْسَهُ مِنَ السُّجُودِ وَإِذَا قَامَ مِنَ الرَّكْعَتَيْنِ» فَقَالَ حُطَيْمٌ عَمَّنْ تَحْفَظُ هَذَا؟ قَالَ عَنِ النَّبِيِّ ﷺ وَأَبِي بَكْرِ وَعُمَرَ ثُمَّ سَكَتَ فَقَالَ لَهُ حَطِيمٌ وَعُثْمَانَ قَالَ وَعُثْمَانَ