Did Umar ibn al-Khattab state that the Prophet (peace be upon him) died without clarifying the matter of usury? And is the hadith "gold for gold and dates for dates" the sole proof regarding usury, and is it among the Ahadith al-Ahad (solitary narrations)?

Intoxicants are derived from five things: grapes, dates, wheat, barley, and honey. Khamr (definition) (wine/intoxicant) is that which clouds the intellect. Umar wished that the Prophet, peace and blessings be upon him, had not departed from them until he had given them instructions regarding the grandfather (in inheritance), kalalah (a deceased person leaving no direct ascendants or descendants), and the chapters on usury, in order to avoid ijtihad (definition) (independent reasoning) and error in these matters. Allah perfected the religion before the Prophet's death, peace and blessings be upon him. The statement of anyone who claims that the Prophet, peace and blessings be upon him, died before the religion was perfected is a grave error. Allah Almighty says: "This day I have perfected for you your religion." The hadith (definition) "gold for gold" is narrated in Sahihayn and other collections, and it has many narrations. It is not the only hadith clarifying the rulings on usury, and the fact that it is an Ahad hadith (a solitary narration) does not undermine its authority.