A friend is both a treasure and a comfort.

朋友既是财富，也是安慰。

Admonish your friends in private, praise them in public.

在私底下要忠告你的朋友，在公开场合又表扬你的朋友。

Set great store by friendship.

情意重千斤。

Between friends all is common.

朋友之间不分彼此。

Old friends and old wine are best.

陈酒味醇，老友情深。

A common danger causes common action.

同仇敌忾。（这句谚语也可以用来形容朋友在困难时刻共同面对挑战。）

Life without a friend is death.

没有朋友，虽生犹死。

Misfortune tests the sincerity of friends.

患难见真情。

A friend in need is a friend indeed.

患难见真情。

To prepare a friend, three things are required: to honor him present, praise him absent, and assist him in his necessities.

维护朋友，有三件事情要做到：当他在场时尊敬他，不在场时表扬他，在他需要帮助时支持他。

这些谚语简单而富有哲理，适合用来称赞朋友或表达对友情的珍视。希望这些谚语能帮助你更好地表达对朋友的赞赏和友谊的重视。