It is difficult to be called a Muslim; if one is truly a Muslim, then he may be called one.
First, let him savor the religion of the Prophet as sweet; then, let his pride of his possessions be scraped away.
Becoming a true Muslim, a disciple of the faith of Mohammed, let him put aside the delusion of death and life.
As he submits to God’s Will, and surrenders to the Creator, he is rid of selfishness and conceit.
And when, O Nanak, he is merciful to all beings, only then shall he be called a Muslim.
— Guru Nanak Dev Ji, Sri Guru Granth Sahib, Section Six: Raag Maajh