Specifically, two women swore to "never dislike each other, to never speak ill of each other, and that they will be nothing but the best of friends" under a witness
I can't answer your question, and you might already know this, but for what it's worth "xwahar xande" is Farsi. It means "sister of laughter". It could also be "xwahar xaande" which would mean "sister of learning".