'Certain' in the Bible

There was a certain man from Ramathaim Zophim, from the hill country of Ephraim, whose name was Elkanah the son of Jeroham, the son of Elihu, the son of Tohu, the son of Zuph, an Ephraimite.

Then Saul said to his uncle, "He told us for certain that the female donkeys had been found." But he did not tell him about the matter of the kingship [of] which Samuel had spoken.

Then Jonathan said, "Far be it from you! For if I know for certain that {my father decided evil should come upon you}, would I not have told it to you?"

So David said to Ahimelech the priest, "The king charged me [with] a matter and said to me, 'No one must know anything about this matter [on] which I am sending you, [with] which I have charged you and the servants.'" So {I have arranged to meet with my servants at a certain place}.

Go, please, make certain again! Find out and see {exactly where he is} and who has seen him there! For they have said to me, 'He [is] very cunning.'

David sent spies, and he learned that Saul had come {for certain}.