Allah's Apostle mentioned the greatest sins or he was asked about the
greatest sins. He 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 (pbuh) 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 Prophetsaid, "the false witness."
Sahih Bukhari: Volume 8, Book 73, Number 8/
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