text.config(state=DISABLED)

from Tkinter import Text
 from idlelib.WidgetRedirector import WidgetRedirector

 class ReadOnlyText(Text):
     def __init__(self, *args, **kwargs):
         Text.__init__(self, *args, **kwargs)
         self.redirector = WidgetRedirector(self)
         self.insert = self.redirector.register("insert", lambda *args, **kw: "break")
         self.delete = self.redirector.register("delete", lambda *args, **kw: "break")

from Tkinter import *
root = Tk()
text = Text(root)
text.insert(END,"Some Text")
text.configure(state='disabled')

text = Text(app, state='disabled', width=44, height=5)

text.configure(state='normal')
text.insert('end', 'Some Text')
text.configure(state='disabled')