Our Gemara on Amud Aleph discusses further the importance of keeping one’s word and honoring verbal agreements:

The verse states: “You shall have an honest balance, honest weights, an honest ephah, and an honest hin.״ But wasn’t a hin included in an ephah, why is it necessary to state both measures? Rather, this is an allusion that serves to say to you that your “yes” (“hen” or “hin” means yes in Aramaic) should be true, and your “no” should be true. It is a mitzvah for one to fulfill his promises. 

Chasam Sofer (Kedoshim Ibid) extends this derash to the first part of the verse, which refers to honest weights and measurements. That is to say, there are times where honesty is a bad thing. As we have discussed many times, it is permissible to lie in order to protect a person’s feelings. However, this can also devolve into rationalizing lies out of convenience or avoidance (see Yevamos 65b and our blog post, Psychology of the Daf, Bava Metzia 23). Therefore, one’s judgment and  weighing of the matter, must also be honest so he does not rationalize.

I will add another derash. One of the Hebrew words used in the verse that enumerates the various measures is Ephah. This word is also a partial homonym to the Hebrew word, “eiphoh - where or how.” Perhaps the verse is also hinting that one’s questions and inquiries ought to be open minded, honest and respectful. People often complain that their spouse does not really listen, and most interpersonal arguments involve two people trying desperately to be heard but not trying as hard to listen. If one listens with genuine curiosity and is ready to really consider the other point of view, this tends to generate more open and empathic dialogue.