“I really enjoyed your speech at the ceremony. I was delighted to listen to you,” Mr Tinubu told South African President Cyril Ramaphosa.
Mr Tinubu has until August 23 to file a convincing response arguing why his school records should not be released to Mr Abubakar.
Mr Tinubu, 70, could find himself explaining yet again his true state of health that has long drawn keen interest from a sceptical public.
“Some people use religion as sentiment, but with adequate education, people are seeing through it now.”
President Muhammadu Buhari on Wednesday met with King Charles III at Buckingham Palace, United Kingdom.
Mr Buhari directed the Nigerian Immigration Service (NIS) to immediately issue the new Nigerians with certificates as appropriate.
Leaders from Ghana, Gabon Verde, Democratic Republic of Congo and Central African Republic will also be speaking.
Floods have damaged half a million homes, affecting about 30 million people and killing over 1,000.
Bola Tinubu insists on primaries that will guarantee a broader acceptance of the individual to be elected, saying any discussions of consensus could plunge the APC into chaos.