Messenger of Allah said: "the key to Salat is the purification, its Tahrim is the Takbir, and its Tahlilis the Taslim, and there is no Salat for one who did not recite Al-Hamd and a Surah in the obligatory (prayer) or other prayers."  

قَالَ رَسُولُ اللَّهِ ﷺ مِفْتَاحُ الصَّلاَةِ الطُّهُورُ وَتَحْرِيمُهَا التَّكْبِيرُ وَتَحْلِيلُهَا التَّسْلِيمُ وَلاَ صَلاَةَ لِمَنْ لَمْ يَقْرَأْ بالْحَمْدُ وَسُورَةٍ _ فِي فَرِيضَةٍ أَوْ غَيْرِهَا