Abdullah ibn Sarh had discovered Muhammad's forgery of the Quran and Muhammad wanted him killed after capturing Mecca.
Watch this comic strip in youtube: http://www.youtube.com/watch?v=P-3iSi2V3UE
Ibn Sarh's book, "Prophet Muhammad Illustrated":
Hindi version: http://prophetmuhammadillustrated.com/hindi.html
Arabic version: http://prophetmuhammadillustrated.com/arabic.html
Indonesian version: http://prophetmuhammadillustrated.com/buku-riwayat-hidup-nabi-muhammad.html
English version: http://prophetmuhammadillustrated.com/the-book.html