Albert Barnes Commentary Exodus 12:44

"but every man`s servant that is bought for money, when thou hast circumcised him, then shall he eat thereof." — Exodus 12:44 (ASV)

Servant - The circumcision of the slave, thus enjoined formally on the first day that Israel became a nation, in accordance with the law given to Abraham, (see the margin reference) made him a true member of the family, equally entitled to all religious privileges. In the household of a priest the slave was even permitted to eat the consecrated food: (Leviticus 22:11).