Mishnah Shevuot 2

¹The laws concerning the discovery of having contracted uncleanness are of two kinds, subdivided into four;[If] he became impure and was aware of it, then he forgot that he had been impure, though he remembered that the food was holy; [If the fact that it was] holy food was unknown to him, though he remembered that he was impure; [If] both were unknown to him; And he ate holy food, and was not aware, and after he had eaten, he became aware: in these cases he brings a sliding scale sacrifice. [[If] he became impure and was aware of it, then he forgot that he had been impure, though he remembered that [he was entering] the Temple; [If the fact that he was entering] the Temple was unknown to him, though he remembered that he was impure; [If] both were hidden from him; And he entered the Temple and was not aware, and after he had gone out, became aware: in these cases he brings a sliding scale sacrifice. ²It is the same whether one [while impure] enters the Temple court or the addition to the Temple court, for additions are not made to the city [of Jerusalem], or to the Temple courts except by the king, prophet, Urim and Thummim, the Sanhedrin of seventy one, and with two [loaves] of thanksgiving, and with song. And the court walks in a procession, the two [loaves] of thanksgiving [being carried] after them, and all Israel [following] behind them. The inner one is eaten, and the outer one is burnt. And as to any addition that was made without all these he who enters it [while impure] is not liable. ³If he became impure while in the Temple court [and was aware of it], and then forgot that he was impure, though he remembered that he was in the Temple; [Or] he forgot that he was in the Temple, though he remembered that he was impure; [Or,] he forgot both; And he prostrated himself, or waited [in the Temple] the time it takes to prostrate; Or went out the long way, he is liable; [If he went out] the shorter way, he is not liable; This is the positive precept concerning the temple for which they [the court] are not liable. ⁴And which is the positive precept concerning a menstruant for which they are liable? [This:] if one cohabited with a [ritually] pure woman, and she said to him: “I have become impure”, and he withdrew immediately, he is liable, because his withdrawal is as pleasant to him as his entry. ⁵Rabbi Eliezer said: “[Scripture says: ‘If any one touch… the carcass of] an impure creeping thing, and it be unknown to him’ (Leviticus 5:2), when the impure creeping thing is unknown to him, he is liable; but he is not liable, when the [fact that he is in the] Temple is unknown to him.” Rabbi Akiba said: “[Scripture says:] ‘and it be hidden from him that he is impure’: when his impurity is unknown to him, he is liable; but he is not liable, when the [fact that he is in the] Temple is unknown to him.” Rabbi Ishmael said: “[Scripture] twice [says:] ‘and it be hidden from him’, in order to make him liable both for the forgetfulness of the impurity and the forgetfulness of the Temple.”