Quran 2:238

Surah Al-Baqara, Verse 238:

حَافِظُوا عَلَى الصَّلَوَاتِ وَالصَّلَاةِ الْوُسْطَىٰ وَقُومُوا لِلَّهِ قَانِتِينَ

Guard strictly (five obligatory) As­Salawât (the prayers) especially the middle Salât (i.e. the best prayer ­ 'Asr).And stand before Allâh with obedience [and do not speak to others during the Salât (prayers).
Reference: Sahih Bukhari (English),Volume 01,10. Times of the Prayer,Hadith 527:-

Narrated Ibn `Umar:( May Allah be pleased with him)
Allah's Apostle said, "Whoever misses the `Asr prayer (intentionally) then it is as if he lost his family and property."
Reference: Sahih Bukhari (English),Volume 01,10. Times of the Prayer,Hadith 528:-

Narrated Abu Al-Mahh:( May Allah be pleased with him)
We were with Buraidah in a battle on a cloudy day and he said, "Offer the `Asr prayer early as the Prophet Salalahu alayhi wa sallam said, "Whoever omits the `Asr prayer, all his (good) deeds will be lost." Surah Al-Baqara, Verse 248:

وَقَالَ لَهُمْ نَبِيُّهُمْ إِنَّ آيَةَ مُلْكِهِ أَن يَأْتِيَكُمُ التَّابُوتُ فِيهِ سَكِينَةٌ مِّن رَّبِّكُمْ وَبَقِيَّةٌ مِّمَّا تَرَكَ آلُ مُوسَىٰ وَآلُ هَارُونَ تَحْمِلُهُ الْمَلَائِكَةُ إِنَّ فِي ذَٰلِكَ لَآيَةً لَّكُمْ إِن كُنتُم مُّؤْمِنِينَ

And their Prophet (Samuel >>) said to them: Verily! The sign of His Kingdom is that there shall come to you At-Tâbût (a wooden box), wherein is Sakinah[] (peace and reassurance) from your Lord and a remnant of that which Musâ (Moses) and Hârûn (Aaron) left behind, carried by the angels. Verily, in this is a sign for you if you are indeed believers.
Reference: Sahih Bukhari (English),Volume 06,61. Virtues of the Qur'an,Hadith 531:-

Narrated Al-Bara'frown emoticon May Allah be pleased with him)
A man was reciting Surat Al-Kahf and his horse was tied with two ropes beside him. A cloud came down and spread over that man, and it kept on coming closer and closer to him till his horse started jumping (as if afraid of something). When it was morning, the man came to the Prophet, and told him of that experience. The Prophet said, "That was As-Sakina (tranquility) which descended because of (the recitation of) the Qur'an."