Why did Muhammad (peace be upon him) choose the Five Pillars?

Muhammad (peace be upon him) is a prophet sent by Allah to lead people from darkness into light, calling to the worship of Allah alone and to noble morals, and forbidding polytheism and base morals. The five pillars of Islam (the two declarations of faith, prayer, fasting, zakat, and pilgrimage) are a revelation from Allah, conveyed by the Prophet (peace be upon him). Each pillar represents a different type of worship and test for the Muslim, combining acts of the heart and tongue, physical acts, financial acts, or a combination thereof, all based on submission to Allah through monotheism.