Islam is a complete programme for life covering the individual’s entire existence. From morning till evening not a single moment of the believer’s life excludes the sphere of Islam. It is only after saying his prayers that he goes to bed at night and when he wakes up early in the morning, he first of all purifies his body. After performing his ablutions he says his fajr (dawn) prayer. This is the beginning of the God-oriented life, which starts with purity and worship. The ensuing hours between morning and noon are meant for economic activities. However, during this period too a believer remembers God constantly. In all matters he adheres strictly to the limits set by God, and in his dealings with people, he is scrupulously honest; in any kind of interaction with others he displays a truly Islamic character. 

Then comes the time for the zuhr (noon) prayer, which is observed in the afternoon. During the prayer the believer renews his attachment to God as a matter of worship. After purifying his body and his spirit he is again ready to join in life’s struggle. And conducting himself throughout as a man of principle, he engages himself in his worldly activities until the time of asr (evening) prayer. He again turns to God in prayer to receive his share in God’s blessings so that this may afford him assistance in the next stage of life.

In this way a believer passes his time until the sun sets and the moment comes for the fourth prayer, called the maghrib prayer at sunset. Once again the believer, abandoning all his activities, turns to God in worship, says the prayer as prescribed, and receives his religious and spiritual sustenance from it. After that, armed with the religious spirit, he again finds himself busy in meeting his worldly-requirements. Now the time comes for the fifth prayer called isha (night prayer). After saying this prayer, the believer goes to bed and, reckoning up his activities of the day he goes to sleep in order that he may make a better start the next morning when he wakes up.

Source: Principles of Islam