https://thornhillkollel.com/wp-content/uploads/2016/06/Pesachim-perek-beis-mishna-3-Chametz-that-is-used-as-a-collateral-an-Chametz-which-is-buried.mp3“Pesachim perek beis mishna 3 Chametz that is used as a collateral an Chametz which is buried”.