Sayyiduna Anas (may Allah be pleased with him) narrates: A man was mentioned before the Prophet (peace and blessings be upon him) for his worship and ijtihad (that is, great diligence in worship). The Prophet (peace and blessings be upon him) said: "How much did that companion of yours remember death?" The people said: "We have not heard him mention death." The Prophet (peace and blessings be upon him) said: "Then your companion is not of that standing."
Al-Bazzar recorded it; its chain contains Yusuf bin Atiyyah, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الزهد / 18207