Romans 4:21

21andκαὶhaving been fully assuredπληροφορηθεὶςthatὅτιwhatὃHe had promisedἐπήγγελταιableδυνατόςHe isἐστινalsoκαὶto doποιῆσαι.

and having been fully assured that what He has promised, He is also able to do.