'Swear' in the Bible

"I swear that not one man of this evil generation will see the good land that I promised to give to your ancestors,

Thou shalt fear the LORD thy God, and serve him, and shalt swear by his name.

Thou shalt fear the LORD thy God; him shalt thou serve, and to him shalt thou cleave, and swear by his name.

Look down from thy holy habitation, from the heavens, and bless thy people Israel, and the land that thou hast given us as thou didst swear unto our fathers, a land flowing with milk and honey!

"I solemnly swear to heaven I say "As certainly as I'm alive and living forever,