'Doubt' in the Bible

So take care to get knowledge of all the secret places where he is taking cover, and be certain to come back to me, and I will go with you: and without doubt, if he is anywhere in the land, I will get him, among all the families of Judah.

Then Saul said to David, May a blessing be on you, David, my son; you will do great things and without doubt you will overcome. Then David went on his way, and Saul went back to his place.