Purification is the key to prayer

the Prophet ﷺ said: "The key to ṣalāh is purification, its taḥrīm (prohibition of all else during it) is through the takbīr (saying Allāhu akbar), and its taḥlīl (permissibily of all else after it) is the taslīm (saying the salām at the end)."  

عَنِ النَّبِيِّ ﷺ قَالَ: «مِفْتَاحُ الصَّلاَةِ الطُّهُورُ، وَتَحْرِيمُهَا التَّكْبِيرُ، وَتَحْلِيلُهَا التَّسْلِيمُ۔»  

Messenger of Allah said: "The key to Paradise is Salat, and the key to Salat is Wudu'."  

قَالَ رَسُولُ اللَّهِ ﷺ مِفْتَاحُ الْجَنَّةِ الصَّلاَةُ وَمِفْتَاحُ الصَّلاَةِ الْوُضُوءُ