RAINBOW. Arabic qausu quzah قوس قوح
“The bow of many colours. Not mentioned in the Qur’an, but in the Traditions. In the book entitled an-Nihayah, it is said that Muhammad forbade his people calling the rainbow qausa quzah, because quzah is one of the names of Satan (one who can assume many characters in order to tempt the sons of men). He enjoined them to call it Qausu ‘llah. God’s bow,” because by it, God has promised to protect the world front a second deluge. (Mujma’u ‘l-Bihar, vol ii. p. 142.)
The Persians call it Kaman-i-Rustum, ” the bow of Rustum” (See Muntaha ‘l-Arab, in loco).
Based on Hughes, Dictionary of Islam