I have his written promise.

我有他的书面承诺。

youdao

An oral agreement is not enough; we must have a written promise.

只有口头协议是不够的；我们必须有一个书面承诺。

youdao

A written promise, sealed or unsealed, may be delivered by the promisor in escrow, conditionally to the promisee, or unconditionally.

书面诺言，无论是否盖印，都可以由诺言人以第三方保管的方式有条件或者无条件地交付受诺人。

youdao

She fashioned her own compensation plan: In lieu of a paycheck, Tix would give her a written promise to pay her if and when venture financing came through.

FORBES: Hire now, pay later

Written out of the promise of the franchise, they were women who reached up to close the gap between what America was and what it could be.

WHITEHOUSE: Presidential Proclamation -- Women's History Month, 2013

Integration Clauses : Any oral promise an employer or its attorney makes to the employee is not binding unless it is written down in the severance agreement that the parties sign.

FORBES: The Top Ten Reasons to Hire a Lawyer to Review Your Severance Agreement