הלכה על חולין 163:5

The laws of the commandment: That which they, may their memory be blessed, said (Chullin 82a) that there is no distinction between it and its child and its child and it (the order is not important). And that which they said (Chullin 83a) that at four periods during the year, one who sells a beast to his fellow must inform him, "I sold the mother for slaughter" - because at these four times, all purchasers presumably buy to slaughter [immediately]. And these are them: the eve of the last holiday of [Sukkot]; the eve of the first holiday of Pesach; the eve of [Shavuot]; and the eve of Rosh HaShanah. And according to the words of Rabbi Yose HaGalili, also on the eve of Yom Kippur in the Galilee. And behold, that which we learned that he needs to inform him - it is specifically the seller that has to inform [of] the thing. But the buyer need not ask, as it is a double doubt for him: Lest it does not have a mother; and [even] if it does, perhaps [the seller] did not sell it for slaughter. And that which they said (Chullin 82a) [regarding] two people that bought a cow and its child - that the one who purchased first, slaughters first; but if the second preceded him and slaughtered against the law, the first is forbidden to slaughter. And the law of slaughtering a cow and two of her children, or her two children and her afterwards; and so [too,] it and her daughter and the daughter of her daughter. And it is permitted to slaughter the mother and the daughter of her daughter, as the Torah only forbade "it and its child."