Hadith 1837
عَنْ عَلِيِّ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((مِفْتَاحُ الصَّلَاةِ الطُّهُورُ وَتَحْرِيمُهَا التَّكْبِيرُ وَتَحْلِيلُهَا التَّسْلِيمُ))
It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: The key to prayer is ablution, its sanctification is Allahu Akbar, and its conclusion is Salam.
Hadith 1838
عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا فِي صِفَةِ صَلَاةِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ بِاللَّيْلِ قَالَتْ: ثُمَّ يَجْلِسُ فَيَتَشَهَّدُ وَيَدْعُو ثُمَّ يُسَلِّمُ تَسْلِيمَةً وَاحِدَةً، السَّلَامُ عَلَيْكُمْ يَرْفَعُ بِهَا صَوْتَهُ يُوقِظُنَا
Sayyida Aisha (may Allah be pleased with her) describing the night prayer of the Messenger of Allah (peace and blessings be upon him) says: Then he (peace be upon him) would sit and recite the Tashahhud and supplicate, and then say "As-salamu ‘alaykum" turning his face to one side, and would raise his voice enough to wake us up.