be a man/woman of his/her word
To be known for upholding one's promises. If Ted said that he'll help you move, then he'll definitely be here—he's a man of his word.
be a man/woman of his/her ˈword
be a person who always does what he/she has promised to do: If he said he’d help you, he will — he’s a man of his word. of (one's) word
Displaying personal dependability: a woman of her word.