Sayyiduna Ammar (may Allah be pleased with him) reports that the Prophet (peace and blessings be upon him) said: "Death is sufficient as an admonisher, and certainty is sufficient as wealth."
Al-Tabarani recorded it; its chain contains al-Rabi' bin Badr, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الزهد / 18204