idiom : common saying > Courtesy on one side only lasts not long.
Contents
To reciprocate
  Explanation: That others will be imposed on their actions to respond.
  Source: "Book of Rites ceremony music" to not come, reciprocate; to not to also reciprocate. "
No. 2
  来而不往非礼也
  Friendship cannot stand always on one side
  拼音: lái ér bù wǎng fēi lǐ yě
  释义: 表示对别人施加于自己的行动将作出反应。
  出处: 《礼记·曲礼上》:“往而不来,非礼也;来而不往,亦非礼也。”
English Expression
  1. :  Courtesy on one side only lasts not long.