The Cow - 2:150
Wherever you set out, turn your face towards the Holy Mosque (for prayer). Wherever you are, turn your faces towards it, so that the people may not criticize you. As for the wrongdoers, do not fear them, but fear Me, so that I may complete My favor upon you and you may reach the truth.
What is the purpose of prayer?
The Cow/2:45
Seek help by enduring hardship (patience) and prayer. Surely this is burdensome to the people, except for those who are reverent.
The Spider/29:45
Read from the Book which We have revealed to you and observe the prayer. For prayer discourages from abominable and evil things. The remembrance of Allah (through prayer) is most important. Allah knows what you do.
Prophet Hud/11:87
"They said: "Shu´ayb, does your prayer require us to give up what our ancestors used to serve or to turn our trade as we wish? You are indeed mild-tempered and wise."
Ta-Ha/20:14
I, yes, I am Allah; there is no god but Me. Serve Me and observe the prayer in remembrance of Me.
The Most High/87:15
He who remembers the name of his Lord and prays.
The Victory/48:29
Muhammad, the Messenger of Allah, and those who are with him are harsh against the disbelievers and merciful among themselves. You see them bowing down and prostrating themselves, asking Allah for His favor and pleasure. On their faces are the marks of prostration. This is their character in the Torah. And in the Gospel they are like a plant that has sprouted and grown strong and thickened and stood up on its stems, delighting the cultivators. He enrages the disbelievers with them. Allah has promised forgiveness and a great reward to those of them who believe and do righteous deeds.