On Friday, French aid group, Action Against Hunger, said jihadists had executed four hostages who had been held since July.
According to the group, the four were among six hostages held by the jihadists. It added that one of its staff and two drivers were among those killed.
The President, in a statement released by his spokesman, Femi Adesina, condemned the “alleged execution” of the aid workers.
He also commiserated with the deceased’s family and loved ones.
“Evil will always be defeated by good at the end of the day. Whatever seeming victory evil records, eventually rebounds on the evildoer. We are resolved to beat evil in this land, and we remain unrelenting till we achieve it,” Buhari said, as quoted by the statement.
The President urged all insurgents once again to lay down their arms, and rejoin decent humanity.
The aid workers had been abducted near Damasak, Borno State, in July, and had been held despite all efforts to secure their release, till their alleged execution.
The United Nations has also condemned the alleged executions.