One of my sisters sent this to me at my absolute lowest point, and since then it always brings me up

I don't know who said it though.
The friends who can be silent with us in a moment of dispair or confusion, who can stay with us in an hour of grief and bereavement, who can tolerate not knowing, not curing, not healing - and face with us the reality of our powerlessness - those are the friends who really care.