مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2283
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas and Ibn 'Umar that they heard the Messenger of Allah (ﷺ) say: "Some people should stop neglecting Jumu’ah or Allah will place a seal on their hearts, then they will be recorded as being among the negligent.”
Musnad Ahmad 2290Its isnad is saheeh]