Quranic verses regarding Prayer :
Fat-h (Victory / Conquest) 48 : 29
Muhammad is the Apostle of Allah; and those who are with him are strong against Unbelievers (but) compassionate amongst each other. Thou wilt see them bow and prostrate themselves (in prayer) seeking Grace from Allah and (His) Good Pleasure. On their faces are their marks (being) the traces of their prostration. This is their similitude in the Torah; and their similitude in the Gospel is: like a seed which sends forth its blade then makes it strong; it then becomes thick and it stands on its own stem (filling) the sowers with wonder and delight. As a result it fills the Unbelievers with rage at him. Allah has promised those among them who believe and do righteous deeds Forgiveness and a great Reward.
Nisaa (Women) 4 :103
When ye pass (congregational) prayers celebrate Allah's praises standing sitting down or lying down on your sides; but when ye are free from danger set up regular prayers: for such prayers are enjoined on believers at stated times.
Taubah (Repentance) 9 :18
The mosques of Allah shall be visited and maintained by such as believe in Allah and the Last Day establish regular prayers and practice regular charity and fear none (at all) except Allah. It is they who are expected to be on true guidance.
Baiyina (The Clear Proof / Evidence) 98 : 5
And they have been commanded no more than this: to worship Allah offering Him sincere devotion being True (in faith); to establish regular Prayer; and to practice regular Charity; and that is the Religion Right and Straight.
Maryam (Mary) 19 : 59-60
Then there has succeeded them a generation which has given up prayers (i.e, made their praycrs to be lost, either by not offering them at all or by not offering them perfectly or by not offering them in their proper fixed times, etc.) and have followed lusts. So they will be thrown in Hell. Except those who repent and believe in the Oneness of Allah and His Messenger, and act righteously.
Al-Maa'oon (Alms)107 : 4-5
Woe unto those performers of prayers (hypocrites) who are unmindful of their prayers (i.e., delay their prayer from its stated fixed time).
Selected Ahadith (Prophetic Narrations) regarding Salaah (Prayer) :
I have been ordered to fight against the people until they testify that there is no one worthy of worship but Allah and that Muhammad is the Messenger of Allah and until they perform the Prayers and pay the Zakah, and if they do so they will have gained protection from me for their lives and property, unless (they do acts that are punishable) in accordance with Islam, and their reckoning will be with Allah Most High.