مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4097
Musnad of Abdullah bin Mas'ood
It was narrated from ”Abdullah bin Ma'qil that His father Maʼqil bin Muqarrin al-Muzani said to Ibn Mas'ood (رضي الله عنه): Did you hear The Messenger of Allah (ﷺ) say: “Regret is repentance"? He said Yes.
Musnad Ahmad 4124Saheeh, this is a hasan isnad. It appears above, 3568]