We knew the finishing of the prayer of the Messenger of Allah ﷺ through takbir. 'Amr (b. Dinar) said: I made a mention of it to Abu Mas'ud. hue he rejected it and said: I never narrated it to you. 'Amr said: He did narrate it before this.
مَا كُنَّا نَعْرِفُ انْقِضَاءَ صَلاَةِ رَسُولِ اللَّهِ ﷺ إِلاَّ بِالتَّكْبِيرِ قَالَ عَمْرٌو فَذَكَرْتُ ذَلِكَ لأَبِي مَعْبَدٍ فَأَنْكَرَهُ وَقَالَ لَمْ أُحَدِّثْكَ بِهَذَا قَالَ عَمْرٌو وَقَدْ أَخْبَرَنِيهِ قَبْلَ ذَلِكَ