I believe there is something in the mind, or in the heart, that shows its approbation when we do right. I give myself this advice: Do not fear truth, let it be so contrary to inclination and feeling. Never give up the search after it: and let me take courage, and try from the bottom of my heart to do that which I believe truth dictates, if it leads me to be a Quaker or not.
~ Elizabeth Fry, 1780-1845

The Quaker testimony of integrity demands a consistency in words and actions with the truth. Indeed, the testimony of Truth (often with a capital T) is an alternate name that has been used historically. Importantly, the truth is not derived from an external authority, whether that be a person or a book. Rather, Quakers seek the truth as revealed within by the Spirit, or, as it is often phrased, by the Inner Light. It is not presumed that any individual has complete and infallible access to truth, but it is assumed that all who seek truth will be rewarded in some degree. That is the focus of Quaker worship, as individuals and as a gathered meeting. As the light begins to reveal truth to us, we are called to live according to that truth.

Integrity is living consistently with the truth. It demands both self-awareness and wholeness. It demands honesty, but goes beyond simply avoiding lies or dishonesty. All our words and actions should reflect the truth, even when they go against popular opinion or social convention. Many examples could pulled from history of Quakers acting in accordance with their deepest sense of the truth. The quote above comes from Elizabeth Fry, a Quaker who was called to work for reform of prisons in England.

More on the testimony of integrity is available on this page from the American Friends Service Committee:

https://www.afsc.org/testimonies/integrity

Image from the Bodleian Libraries, Oxford University, used under a Creative Commons Attribution 4.0 International license