'First born' in the Bible

By faith, he hath kept the passover and the besmearing of the blood, lest, he that was destroying the first-born, should be touching them.

Lest there be any fornicator, or profane person, like Esau, - who, for the sake of one meal, yielded up his own firstborn rights;

in high festival, - and unto an assembly of firstborn ones, enrolled in the heavens, - and unto God, judge of all, - and unto the spirits of righteous ones made perfect, -