'Certain' in the Bible

Say to the children of Israel, Let certain towns be marked out as safe places, as I said to you by the mouth of Moses,

And Phinehas, the son of Eleazar the priest, said to the children of Reuben and the children of Gad and the children of Manasseh, Now we are certain that the Lord is among us, because you have not done this wrong against the Lord: and you have kept us from falling into the hands of the Lord.

Then you may be certain that the Lord your God will not go on driving these nations out from before you; but they will become a danger and a cause of sin to you, a whip for your sides and thorns in your eyes, till you are cut off from this good land which the Lord your God has given you.

Now I am about to go the way of all the earth: and you have seen and are certain, all of you, in your hearts and souls, that in all the good things which the Lord said about you, he has kept faith with you; everything has come true for you