Chapter 30 of Numbers gives an elaborate system for determining the validity of promises, oaths and vows. The basic position, however, is simple: do what you say you will do.

When a man makes a vow to the Lord, or swears an oath to bind himself by a pledge, he shall not break his word; he shall do according to all that proceeds out of his mouth. (Num. 30:2)

Elaborations are given to handle exceptions to the rule when someone makes a promise that exceeds their authority. (The regulations in the text deal with situations where certain women are subject to the authority of particular men.) Although the exceptions are valid—you can’t enforce the promise of a person who lacks the authority to make it in the first place—when Jesus commented on this passage, he proposed a much simpler rule of thumb: don’t make promises you can’t or won’t keep (Matthew 5:33-37).

Work-related commitments tempt us to pile up elaborations, qualifications, exceptions, and justifications for not doing what we promise. No doubt many of them are reasonable, such as force majeure clauses in contracts, which excuse a party from fulfilling its obligations if prevented by court orders, natural disasters, and the like. It doesn’t stop at honoring the letter of the contract. Many agreements are made with a handshake. Sometimes there are loopholes. Can we learn to honor the intent of the agreement and not just the letter of the law? Trust is the ingredient that makes workplaces work, and trust is impossible if we promise more than we can deliver, or deliver less than we promise. This is not only a fact of life, but a command of the Lord.