Inara wears these red pajamas first in Shindig:
More after the break...
Some more screencaps from Shindig:
And some screencaps from Objects in Space:
EDIT: And since it seems silly to add another page for what boils down to a towel, Inara's bath scene "robe".
My Photobucket Album for Inara.
Serenifly Costumes site for Inara.