'Solemn' in the Bible

They went to the high priests and elders and said, "We have taken a solemn oath not to taste any food before we have killed Paul.

So in my anger I swore a solemn oath that they would never enter my rest."

We who have believed are entering that rest, just as he has said, "So in my anger I swore a solemn oath that they would never enter my rest,"