مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3709
Musnad of Abdullah bin Mas'ood
It was narrated that 'Abdullah (رضي الله عنه) said: The Messenger of Allah (ﷺ) said: “I have given you permission to lift the curtain and to listen to my private conversation until I tell you not to."
Musnad Ahmad 3732A saheeh hadeeth, and Muslim (2169) this is a da'eef isnad]