Source: lesson 4 from the book study, Usool us-Sittah (The Six Principles), Posted by Islam Tees on 24th September 2019.

Full lesson (mp3 audio) can be downloaded here:
https://islamtees.uk/2019/09/24/free-audio-available-usool-us-sittah-the-six-principles-lesson-4/

The link above also contains transcribed notes taken from the lesson (by Abu Yahya Imran Rafiq) and which contains a concise summary of it.