First of all, it should be clear that Prayer is the cornerstone of religion. In this context, the Prophet, peace and blessings be upon him, said, “Prayer is the cornerstone of religion…” In Islam, Prayer stands as the second pillar of Islam after testifying that there is no god but Allah and Muhammad is His final Messenger. The Prophet, peace and blessings be upon him, said, “Islam is built upon five pillars: testifying that there is no true god except Allah and that Muhammad is the Messenger of Allah, performing Prayer, paying the Zakah, making the pilgrimage to the Sacred House (Hajj), and fasting the month of Ramadan.”
A Muslim cannot tell his fellow Muslim, who commits some sins, to stop offering Prayers. Rather, he has to help him give up sins.
Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: “Prayer, in itself, is the best thing a person can do in this world; there is nothing better a person can do than pray at the time of Prayer.
We should never tell a person who is praying to stop praying. However, if a person is praying and yet persisting in sins, the question is: Why is he acting against the spirit of Prayer? It could be that the person is not praying properly, or he is not aware of the effect of prayer and its significance. If a person is praying properly, it is bound to refine the internal and external of the person. Prayer instills the consciousness of Allah and reminds a person of his accountability to his Creator.
Therefore, if he conditions himself to pray consciously and in the proper spirit, visualizing the meaning and significance of Salah (Prayer), he must, sooner or later, eventually give up all sins.
It is, therefore, the Islamic duty of his brothers to remind him to be true to the spirit of Salah. Ultimately it is only Prayer that will help a person give up sins. Allah says, “Verily Prayer restrains (a person) from acts of lewdness and vices.” (Al-`Ankabut: 45)
Also, the Prophet, peace and blessings be upon him, told us that praying five times a day is bound to cleanse a person thoroughly (both morally and spiritually), just as bathing five times a day in a pool of fresh water rids a person of all of his physical impurities.”