Yup. It’s not like Michelle Obama coined the centuries-old idiom. No one demanded she cite it when she used it...nor the other one, which is a typical description of rising from a hard-scrabble early life.
I found this quote (someone posted referring to it) from the movie John Q (2002):
“When you say you’re gonna do something, you do it. Because your word is your bond, son, that’s all you have.”