Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
heaven [ˈhɛvn] n (also fig) рай#
thank heaven(s)! сла́ва Бо́гу!
heaven forbid! Бо́же упаси́!
for heaven's sake! ра́ди Бо́га!
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.