Buhari described her as a woman with a good heart, who stood by her convictions, and gave sacrificially.
This is contained in a statement issued in Abuja on Saturday by Mr Femi Adesina, Special Adviser on Media and Publicity to the president.
The statement recalled that late Koko, who had waited nine hours in Kebbi early 2015, to donate one million naira to Buhari as the then presidential candidate of the All Progressives Congress (APC).
Buhari described her as ``a woman with a good heart, who stood by her convictions, and gave sacrificially.
``Hajiya Koko had offered virtually her life's savings to candidate Buhari then, saying she admired his honesty, discipline, and stand for truth.’’
Receiving the news of her passage, President Buhari commended Koko's conviction and sacrificial giving, urging Nigerians to learn vital lessons from her life.
``She gave practically all she had towards our campaign. Though well advanced in age, she still believed a new Nigeria was possible, and followed her conviction with action.
``What generosity of spirit and what tenacious faith in her motherland. Nigerians, old and young, have a lot to learn from her,’’ he said.
The president condoled with the family and relations of the departed.
He urged them to take solace in the fact that their matriarch lived to a ripe old age, ``and she saw the beginning of the change she had long yearned for.
``The onus is now on all of us to ensure that the change gets entrenched and solidified for even generations yet unborn to benefit from.’’
The President also sympathised with the governor and people of Kebbi, whom he said would all miss the sterling qualities of Koko.
Buhari said that the life of the departed would serve as a standard to emulate in the service of God, humanity and country.
He prayed that Allah would grant her soul repose in Al-jannah.