Mustadrak al-Hakim — Hadith 167

It is narrated from al-Hasan al-Basri that a Bedouin came to Sayyiduna Umar (may Allah be pleased with him) and asked him about the religion: O Commander of the Believers, teach me the religion. He said: Bear witness that there is no god but Allah and that Muhammad ((peace and blessings be upon him)) is the Messenger of Allah, establish the prayer, give the zakah, fast Ramadan and perform Hajj to the House (of Allah). Hold to what is done openly, and beware of what is done in secret, and beware of everything one would be ashamed of (before people). The man said: When I meet Allah, I will say: Umar bin al-Khattab commanded me to do this. He said: O servant of Allah, hold fast to this, and when you meet Allah, say whatever you wish.
Imam al-Qabbani says: I asked Muhammad bin Yahya which of the two narrations is the preserved one (mahfuz): the hadith of Yunus from al-Hasan from Umar, or Nafi' from Ibn Umar? He said: The narration of al-Hasan is more likely.
Imam al-Hakim says: May Allah be pleased with Muhammad bin Yahya; he refrained from answering out of scrupulousness, wary of going against his saying ((peace and blessings be upon him)): "Leave what makes you doubt for what does not make you doubt." Had he reflected on the two narrations, it would have become clear to him that their wordings are different: they are two musnad hadiths and a report. Nothing is preserved from Ubaydullah from Yunus bin Ubayd except the hadith about leadership, and al-Darawardi alone narrated it. Sa'id bin Abd al-Rahman al-Jumahi is trustworthy and reliable, and others besides Muhammad bin al-Sabbah have narrated it from him, although Muhammad bin al-Sabbah is also trustworthy and reliable.