a man of his word
A man who can be expected to keep or follow through with his promises or intentions; a truthful, trustworthy, or reliable person. (Feminine: "a woman of her word.") Bob, I'm a man of my word. If I tell you I'll be at your house tomorrow morning at 10, then that's when I'll be there. I've found Martin to be a man of his word so far, so I'm confident he'll get us the best deal possible.
man of his word
A man who keeps promises, who can be trusted, as in You can count on Rudy-he's a man of his word. This expression, which uses word in the sense of "a promise or undertaking," was first recorded in 1542.
a man (or woman) of his (or her) word
a person who keeps the promises that they make.