مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3581
Musnad of Abdullah bin Mas'ood
It was narrated that ‘Abdullah (رضي الله عنه) said: Some people said: O Messenger of Allah, will we be blamed for our deeds during the jahiliyyah? He said: “Whoever among you does well in Islam will not be blamed for it, but whoever does badly will be blamed for his earlier and later actions."
Musnad Ahmad 3604Its isnad is saheeh, al-Bukhari (6921) and Muslim (120)]