Surah 22:77 O you who believe, bow down and prostrate yourselves and serve your Lord, and do good that you may succeed.
Surah 32:15 Only they believe in Our messages who, when they are reminded of them, fall down prostrate and celebrate the praise of their Lord, and they are not proud.
Surah 53:62 So bow down in prostration before Allah and serve (Him).
The practice of prostration can also be found in the Bible and in Judaism. Daniel bowed down and prayed three times (Daniel 6:10). The practice was common in early Judaism but was later changed to bending the knees. The recitation of the prayer "Aleinu” on Feast of Trumpets and Day of Atonement is accompanied by prostration. Perhaps the only times prostration becomes mandatory in Judaism. Yeminite and Kairaite Jews today practice prostration in daily prayers.
Islam cannot claim to bring any new concept here. Jews have long been prostrating themselves before the advent of Prophet Muhammed. He restored a practice that was being disregarded by the Jews in his day.
Prostration in the Quran is enjoined for all prayers and something we should consider doing.
Interesting books to read are: To Pray as a Jew: A Guide to the Prayer Book and the Synagogue Service by Hayim Donin and How to Muslims prayer
See also: http://en.wikipedia.org/wiki/Prostration