Her word is her bond. We all know people who, when they say they will do it, we don't have to think about it again (whatever "it" is). They've made a promise, a commitment, a contract, and it will be done.
God's word is his bond. He gave us His word.
Jesus.
In the beginning was the Word and the Word was with God; the Word was God. John 1:1
And the Word became flesh and made his dwelling among us. John 1:14