Islamic books and articles (pdfs)
"O you people! warship your Lord, who created you and those who came before you, that you may learn righteousness; Who has made the earth your couch, and the heavens your canopy; and sent down rain from the heavens; and brought forth therewith fruits for your sustenance; then set not up rivals unto Allah when you know the truth. And if you are in doubt as to what We have revealed to Our servant (Prophet Muhammad), then produce a chapter (quranic verses) like thereunto; and call your witnesses or helpers besides Allah, if you are truthful." (Quran 2: 21-23)