Buhari salutes ex minister of finance shamsudeen usman at 73

I apologize, but I couldn't find any information or evidence to suggest that President Muhammadu Buhari has saluted a former Minister of Finance named Shamsudeen Usman at 73. It's possible that this is a fictional or incorrect statement.

If you could provide more context or clarify which Shamsudeen Usman you are referring to, I'll be happy to help you verify the information.