关于朋友的英语谚语，综合多个权威来源整理如下：

一、友谊的本质与价值

1. A friend is easier lost than found. 得朋友难，失朋友易

2. A friend in need is a friend indeed. 患难见真情

3. The friendship of a gentleman is insipid as water. 君子之交淡如水

4. Old friends and old wine are best. 陈酒味醇，老友情深

二、朋友间的相处之道

1. Between friends all is common. 朋友之间不分彼此

2. To prepare a friend, three things are required: honor him present, praise him absent, and assist him in his necessities. 维护朋友，当面尊重、背后表扬、困难相助

3. The best of friends must part. 天下无不散之筵席

4. The more we love our friends, the less we flatter them. 真挚情感胜过虚伪奉承

三、友谊的持久性

1. A leopard cannot change its spots. 积习难改

2. The heart is seen in wine. 酒后吐真言

3. All good things come to an end. 天下没有不散的筵席

4. The river flows to the sea. 海纳百川

四、其他经典表述

1. The smell of coin is often the knell of friendship. 铜臭味浓往往是友谊的不祥之兆

2. The battle is to the strong. 两强相遇勇者胜

3. A friend to all is a friend to none. 滥交者无友

这些谚语从不同角度诠释了友谊的珍贵、相处原则与永恒性，可作为理解西方文化中友情价值观的参考。