The Table Spread - 5:6
Believers! When you rise for prayer, wash your faces and your hands up to the elbows. Splash your head, and your feet up to the heels, and wash if you have had sexual intercourse. And if you are sick or a traveler, or you have come from the toilet, or you have had sexual intercourse with women and you cannot find water, then turn to a clean piece of earth and rub your face and arms with it. Allah does not wish to cause you any hardship. He only wants to purify you and complete His favor upon you. That you may give thanks.
The most important criterion of belief:
The Cattle/6:82
Those who believe and do not mix their faith with wrongdoing, they deserve security and they have found the truth.
Luqman/31:13
"When Lokman advised his son, he said: "My dear son, do not associate partners with Allah; surely shirk (associating partners with God) is a great wrong."
The Companies/39:65
It has been revealed to you and those before you that if you associate partners, all that you do will be in vain and you will be of the losers.