在 / 古代 / 结拜 / 兄弟 / 时 / 双方 / 要 / 换帖 / 写下 / 生辰八字

在古代，结拜兄弟时，双方要换帖，写下生辰八字。

In ancient times, when swearing brotherhood, both parties would exchange cards with their birth details.