The tractate Yaddayim addresses ritual hand-washing (Netilath Yaddayim), an ordinance established by the Sages to promote vigilance and prevent violation of Torah purity laws.
According to the Torah, impurity affects the entire body, rendering the concept of isolated hand impurity contradictory—either a person is fully impure or not impure at all.
The Sages instituted a lesser, rabbinic form of hand impurity (Tumath Yaddayim), designed to safeguard sacred items like sacrificial meat and Terumah ,the produce donated by farmers to priests, by requiring hand-washing before handling them.
The ordinance was first enacted during the First Temple period*Babylonian Talmud Shabbath 14b, requiring immersion of the hands in a body of water, such as a Mikveh, before handling or consuming sacrificial meat, which possesses greater sanctity than Terumah*Mishna Chagigah 2:5.
In the early Second Temple era, the Sages expanded the ordinance to require that water be poured upon hands before they interact with Terumah*Babylonian Talmud Shabbath 15a, which is of lesser sanctity than sacrificial meat.
Later, further restrictions were added, requiring hand-washing before consuming certain profane foods—specifically bread or wet vegetables—to maintain general awareness of purity laws among laypeople.
Stage 1: Torah Law
Immersion in a Mikveh is required for Sacrificial Meat and Terumah, along with a further purification ritual if the priest came into contact with a dead body.
Stage 2: First Temple
Rabbinical introduction of immersing the hands in a Mikveh prior to eating Sacrificial Meat, after each lapse in mindfulness after immersing the entire body in a Mikveh.
Stage 3: Early Second Temple
Rabbinical introduction of pouring water onto the hands (Netilath Yaddayim) or immersing them in a Mikveh prior to eating Terumah, after each lapse in mindfulness after immersing the entire body in a Mikveh.
Stage 4: Late/Post Second Temple
Rabbinical introduction of pouring water onto the hands (Netilath Yaddayim) or immersing them in a Mikveh prior to eating bread or wet vegetables.