عن أبي هريرة رضي الله عنه قَالَ: قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم : "لاَ يَقْبَل الله صلاَة أَحَدِكُم إِذا أَحْدَث حَتَّى يَتوضَّأ".
[صحيح] - [متفق عليه]
Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Allah does not accept the prayer of anyone of you who is in the state of Hadath (minor ritual impurity), until he performs ablution."
Sahih/Authentic. - [Al-Bukhari and Muslim]
The wise legislator ordered that anyone who wants to pray must only pray when they are in a good and a beautiful state, because prayer is the firmly established connection between the Lord and His servant. It is the servant's channel to have a confidential talk with Allah. So Muslims are ordered to perform ablution and be free from impurities during prayer, and informed that without purification, the prayer is rejected and not accepted.