Tum Na Badalna

You might have seen the Dev Anand mega hit film 'Guide'.
In the film there is a famous song 'gaata rahe mera dil...'
In this song, Waheeda Rehman wears a pink saree and throughout  the song wears the same dress.
So when we have a trend of heroines changing clothes every sequence, the big question is:
Why doesnt Waheda Rehman change her saree throughout the entire song?
 

The answer is pretty simple...........

Coz in the first stanza of the song, Dev Anand sings:
'Oo mere humrahi,
meri bah thamen chalna,
badle duniya 'saree'
tum na badalna...'