'Firstborn of Israel' in the Bible

These are the heads of their ancestors' households: the sons of Reuben, the firstborn of Israel: Hanoch and Pallu; Hezron and Carmi.

The genealogies of the descendants of Reuben, the firstborn of Israel, were recorded individually, according to their tribes and ancestral houses, as were the names of all the men 20 years and above who could serve in the army.

since every firstborn of Israel belongs to me, from human beings to livestock. On the same day that I destroyed all the firstborn in the land of Egypt, I consecrated them to myself,