keep (one's) word
To do as one has promised. Tom always keeps his word, so if he promised to help you move, then he'll be here.
keep one's word
to uphold one's promise; to do as one says. (The opposite of break one's word.) I told her I'd be there to pick her up, and I intend to keep my word. Keeping one's word is necessary in the legal profession.
keep/break your ˈword
do/fail to do what you have promised: Do you think she’ll break her word and tell everyone?