Charles Ellicott Commentary Leviticus 22:13

"But if a priest`s daughter be a widow, or divorced, and have no child, and be returned unto her father`s house, as in her youth, she shall eat of her father`s bread: but there shall no stranger eat thereof." — Leviticus 22:13 (ASV)

Be a widow, or divorced, and have no child. — An exception, however, to this rule is when the priest’s married daughter loses her husband either by death or by divorce, and has no children; under such circumstances she may resume her family ties under her paternal roof. Having lost her bread supplier, she may eat again her father’s bread. She could, however, only eat of the heave-offerings, but not of the wave-breast and heave-shoulder.

Returned to her father’s house, as in her youth. — As an inference from these words, two canons were enacted during the second Temple:

1. If she is left a widow in this way without children, her departed husband has a surviving brother who, according to the law, must marry his sister-in-law , and she is reserved for him, she cannot partake of the holy things, though she has temporarily returned to her father’s house. Hence the Chaldee version renders this clause, returned to her father’s house, and is not reserved for her husband’s brother.
2. And if she is pregnant at the death of her husband and, on her return home, she must not eat of the holy things. If the child dies, she is then permitted to be reincorporated into her father’s family.