手足之情

Explanation: Hand, Foot: metaphor brother. Analogy brother's feelings. 　　Usage: Partial official; as subject, object; with compliment 　　Source: Song Zhe, "to imprison a letter for the brother of Su Shi": "Ai-chi Chen theft, numerous brotherhood, and are thus risking a word." Thesaurus:  be bound together like brothers and sisters, Auxiliary car dependency, as well blended as milk and water, be finger and glove with sb., Trinity, As close as body, One turn, brotherly feeling