Said to be a sign of God's promise after the flood not to destroy the earth again (Gen. 9: 12–13) and its beauty is to be praised (Ecclus. [= Sir.] 43: 11); it is part of the glory surrounding God (Rev. 10: 1).
Citation for rainbow
Citation styles are based on the Chicago Manual of Style, 15th Ed., and the MLA Style Manual, 2nd Ed..
MLA
"rainbow." In A Dictionary of the Bible. Ed. W. R. F. Browning. Oxford Biblical Studies Online. Jun 20, 2013. <http://www.oxfordbiblicalcstudies.com/article/opr/t94/e1582>.
Chicago
"rainbow." In A Dictionary of the Bible. , edited by W. R. F. Browning. Oxford Biblical Studies Online, http://www.oxfordbiblicalcstudies.com/article/opr/t94/e1582 (accessed Jun 20, 2013).