Salat (prayer) is the main pillar of Islam and at the head of all acts of obedience. There are very many hadith narrated regarding the virtues of prayer and of the one who fulfills its manners and the fearful concentration (khushoo') which it requires.
مسلم
حَدَّثَنَا إِسْحَقُ بْنُ سَعِيدِ بْنِ عَمْرِو بْنِ سَعِيدِ بْنِ الْعَاصِ حَدَّثَنِي أَبِي عَنْ أَبِيهِ قَالَ كُنْتُ عِنْدَ عُثْمَانَ فَدَعَا بِطَهُورٍ فَقَالَ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ مَا مِنْ امْرِئٍ مُسْلِمٍ تَحْضُرُهُ صَلَاةٌ مَكْتُوبَةٌ فَيُحْسِنُ وُضُوءَهَا وَخُشُوعَهَا وَرُكُوعَهَا إِلَّا كَانَتْ كَفَّارَةً لِمَا قَبْلَهَا مِنْ الذُّنُوبِ مَا لَمْ يُؤْتِ كَبِيرَةً وَذَلِكَ الدَّهْرَ كُلَّهُ
.. I heard Allah's Messenger (sas) say: "There is no one upon whom the time for one of the prescribed prayers comes and who does well its ablutions and its fearful concentration and its bowing but that it is an expiation for him for all that came before it as long as no major sins were committed - and that is for all time."
البخاري
عَنْ ابْنِ شِهَابٍ أَنَّ عَطَاءَ بْنَ يَزِيدَ أَخْبَرَهُ أَنَّ حُمْرَانَ مَوْلَى عُثْمَانَ أَخْبَرَهُ أَنَّهُ رَأَى عُثْمَانَ بْنَ عَفَّانَ دَعَا بِإِنَاءٍ فَأَفْرَغَ عَلَى كَفَّيْهِ ثَلَاثَ مِرَارٍ فَغَسَلَهُمَا ثُمَّ أَدْخَلَ يَمِينَهُ فِي الْإِنَاءِ فَمَضْمَضَ وَاسْتَنْشَقَ ثُمَّ غَسَلَ وَجْهَهُ ثَلَاثًا وَيَدَيْهِ إِلَى الْمِرْفَقَيْنِ ثَلَاثَ مِرَارٍ ثُمَّ مَسَحَ بِرَأْسِهِ ثُمَّ غَسَلَ رِجْلَيْهِ ثَلَاثَ مِرَارٍ إِلَى الْكَعْبَيْنِ ثُمَّ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَنْ تَوَضَّأَ نَحْوَ وُضُوئِي هَذَا ثُمَّ صَلَّى رَكْعَتَيْنِ لَا يُحَدِّثُ فِيهِمَا نَفْسَهُ غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ
From Ibn Shihab that Ataa' ibn Yazid informed him that Humran mawlaa Uthman informed him that he saw Uthman ibn Affaan called for a vessel of wtaer, poured it on his hands three times and washed them. Then he put his right hand into to container and rinsed his mouth and washed out his nose and mouth. Then he washed his face three times and his arms up to the elbows three times then he wiped over his head and washed his feet three times up to the ankle bones. Then he said that Allah's Messenger (sas) said: "Whoever made ablution in the manner of this ablution of mine and then prayed two rakaats without speaking to himself therein, will have his prior sins forgiven."
Maimoon ibn Mahraan said: I never saw Muslim ibn Yasaar distracted in his prayer ever. Once, one side of the masjid caved in such that the people in the sooq were startled by its noise. He was in the masjid praying and did not even glance in any direction. In his house, the people of his household used to become silent when he entered, but when he began to pray, they spoke aloud and laughed.
KNOW that the prayer his pillars, obligatory parts and sunan. The soul of salat is intention, sincerity, khushoo' (a state including humility, fear, concentration and focus) and attentiveness of the heart. Salat contains adhkaar (statements of remembrance of Allah, praise and gratitude), "conference" with Allah and certain actions. Without khushoo', the intention behind these statements of remembrance and this conference with Allah cannot happen. If the meaning of standing is being in service to Allah and the meaning of bowing and prostrating and bowing is humbling oneself before Allah and glorifying Him but the heart is not present and attentive, then the meaning of the prayer and the intention behind it has not been fulfilled. Any action which does not fulfill its intention is just a form or a picture which has no meaning. Allah said, speaking about the animal sacrifices which he commanded during the Pilgrimage:
