杵臼之交

Explanation: Pestle: Tsuishine the stick; mortar: mortar. Friends do not care about rich and poor analogy and identity. 　　Usage: Partial official; as object; that the friendship does not count and rank 　　Source: Southern Song Fan Ye "Han Wu Yu Chuan": "Shamu the public to tour the Imperial College, no MERITS, is changing clothes off commission for the lease woo Chung. Woo with words shocked, and then were scheduled to meet at Chujiu of room. " Thesaurus:  Friendship of shared, the friendship between gentlemen is as pure as crystal; a hedge between keeps friendship green