"counsel, advice," Old English ræd "advice, counsel," from Proto-Germanic *redin (source also of Old Saxon rad "advice, counsel, help, advantage," Old Frisian red "council, advice," Dutch raad "advice, counsel," German Rat "advice, counsel," Old Norse rað "advice, consideration, remedy, power; marriage"), from the source of read (v.), which originally meant "to advise, counsel." A very frequent word in Old English and early Middle English, falling from literary use 17c. until revived somewhat in 19th century archaic and poetic diction.
The verb read in the already obsolete sense ' counsel, advise,' was much affected by Spenser, and in the early modern and ME. spelling rede which he used has likewise been much affected by his archaizing imitators; but there is no historical ground for a difference in spelling. [Century Dictionary]