'Solemn' in the Bible

So Abraham instructed his servant, who was the oldest member of his household and in charge of everything he owned, "Make this solemn oath to me

So the servant made a solemn oath to his master Abraham regarding this matter.

Remain in this land, and I'll be with and bless you by giving all these lands to you and to your descendants in fulfillment of my solemn promise that I made to your father Abraham.

Then he made this solemn vow: "If God remains with me, watches over me throughout this journey that I'm taking, gives me food to eat and clothes to wear,

As the time approached for Israel to die, he called for his son Joseph and addressed him. "Please," he asked, "if you're happy with me, make a solemn promise that you'll treat me fairly and kindly by not burying me in Egypt.