|Ex-military ruler Abdussalami Abubaker brokered the deal Thursday Morning|
Ex-military ruler Abdussalami Abubaker brokered the deal.
Nigeria's Peace Committee raised concerns on Monday that campaigning had been marred by hate speech. Some 800 people were killed after the disputed 2011 elections.
Mr Jonathan is facing a strong challenge from Gen Buhari, with some analysts predicting a photo-finish. In 2011, official figures said Mr Jonathan won by a wide margin.
Gen Buhari said those results were fraudulent, and violence broke out in his mainly northern strongholds. On Wednesday, Nigeria's government ordered the closure of all land and sea borders to ensure a peaceful election.
Checkout images from the Peace Deal Ceremony: