your, his, etc. word is your, his, etc. bond
(one's) word is (one's) bond
One always keeps one's promises. I promise that I'll be there in time with the money for the deposit: my word is my bond.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
your, his, etc. ˌword is (as ˌgood as) your, his, etc. ˈbond
used to say that somebody always does what they promise to do: Don’t worry, you can trust my brother. His word’s as good as his bond.Farlex Partner Idioms Dictionary © Farlex 2017