man of his word
US /mæn əv hɪz wɜrd/
UK /mæn əv hɪz wɜrd/

1.
a person who always keeps their promises and can be trusted
:
•
You can rely on him; he's a true man of his word.
•
My father taught me to always be a man of my word.
a person who always keeps their promises and can be trusted