take someone's word for it idiom (also take someone at their word)
B2 相信（某人）的话
to believe that what someone says is true
He said he'd give me a job and I just took him at his word. 他说过会给我一份工作，而我就信以为真了。
If he says there's $500 in the envelope, then I'll take his word for it. 如果他说信封里有500美元，那我会相信他说的话。