עצור! גבול לפניך

And it came to pass after these things, that God did prove Abraham, and said unto him: ‘Abraham’; and he said: ‘Here am I.’ And He said: ‘Take now thy son, thine only son, whom thou lovest, even Isaac, and get thee into the land of Moriah; and offer him there for a burnt-offering upon one of the mountains which I will tell thee of.’ And Abraham rose early in the morning, and saddled his ass, and took two of his young men with him, and Isaac his son; and he cleaved the wood for the burnt-offering, and rose up, and went unto the place of which God had told him.

Beth Shammai permits the rival wives to the surviving brothers, and Beth Hillel prohibits them. If they perform the halitzah, Beth Shammai disqualifies them from marrying a priest, and Beth Hillel makes the eligible. If they performed yibbum, Beth Shammai makes them eligible [to marry a priest], and Beth Hillel disqualifies them. Though these forbid and these permit, and these disqualify and these make eligible, Beth Shammai did not refrain from marrying women from [the families of] Beth Hillel, nor did Beth Hillel [refrain from marrying women] from [the families of] Beth Shammai. [With regard to] purity and impurity, which these declare pure and the others declare impure, neither of them refrained from using the utensils of the others for the preparation of food that was ritually clean.