4:36 AND WORSHIP Allah ( God alone), and do not ascribe divinity, in any way, to aught beside Him. And do good unto your parents, and near of kin, and unto orphans, and the needy, and the neighbour from among your own people, and the neighbour who is a stranger, and the friend by your side, and the wayfarer, and those whom you rightfully possess. Verily, Allah does not love any of those who, full of self-conceit, act in a boastful manner; (Quran 4:36) (Translation)
Bukhari Volume 8, Book 73, Number 8:
Narrated Anas bin Malik:Allah's Apostle (saw) mentioned the greatest sins or he was asked about the greatest sins. He (saw)said, "To join partners in worship with Allah; to kill a soul which Allah has forbidden to kill; and to be undutiful or unkind to one's parents." The Prophet (saw) added, "Shall I inform you of the biggest of the great sins? That is the forged statement or the false witness." Shu'ba (the sub-narrator) states that most probably the Prophet (saw) said, "the false witness." What is Islam ?Islam is not a new religion, but the same truth that God revealed through all His prophets to every people. For a fifth of the world's population, Islam is both a religion and a complete way of life. Muslims follow a religion of peace, mercy, and forgiveness, and the majority have nothing to do with the extremely grave events which have come to be associated with their faith.