In which ancient book did "friend" and "confidant" first appear? What is the explanation?

1, confidant-"Friends all over the world, several confidants are together", "A scholar dies for a confidant"

2. girlfriends-the closest friends, intimate friends who talk about everything.

3. Best friends-organizations established with the same interests or purposes will all die together.

4. Friends-a friendship between gentlemen is as light as water.