It is evident from the composition of biblical genealogies that the status of bekhor was a pervasive feature of Israelite life. In many such lists there is a formula which specifies the status of the first-listed son. For example, Numbers 1:20: "The sons of Reuben, the firstborn of Israel, were…" (cf. e.g., Gen. 35:23; 36:15; Ex. 6:14, and frequently in the genealogies of I Chron.). Even in genealogies which do not specifically indicate the status of the first son listed, it is clear that he is the firstborn. There are suggestions in the Bible that primogeniture carried certain duties and privileges in addition to the estate rights (see Gen. 27; 48:13; Judg. 8:20; I Chron. 26:10, etc.). The second in line was termed ha-mishneh (I Sam. 17:13; II Sam. 3:3; I Chron. 5:12).
The status of the firstborn in royal succession is not clearly defined. The Israelite kings were often polygamous, and the relative status of several royal wives figured in determining a succession, making the Deuteronomic law cited above appear more like an ideal than a reality so far as the king was concerned. A king might, for a variety of reasons, also be disposed to officially reject one of his sons, Accordingly, there were instances where the first in the royal line of succession did not, in fact, succeed his father. It is not known whether the firstborn in families of the high priests had a special status. From the exception noted in I Chronicles 26:10 it is inferable that the firstborn of a levitical clan was normally placed in charge of his brothers. There is some evidence that the first-born daughter (bekhirah) was customarily married off before her younger sisters (Gen. 29:16ff.; I Sam. 18:17ff.).