"Recite what is sent of the book (Quran) by revelation to you and establish regular prayer, for prayer keeps you away from shameful and unjust deeds (sins)" ~ Quran - chapter 29, verse 45
"Say (O Mohamed) to Ibadi (my servants) who have believed, that they should perform as-salah (prayers) and spend in charity out of the sustenance" ~ Quran - chapter 14, verse 31
Hadrat Abu Huraira (may Allah be pleased with him) reported that Allah's Prophetic Messenger (may Allah's blessings and peace be upon him) said, "A servant becomes nearest to his Lord while he is in prostration (before Him). So increase supplication." (Muslim)