The Amidah, the standing prayer, said silently while facing Jerusalem with the feet together, is the fixed centre of every Jewish prayer service, so central that it is often called simply ha-tefillah, the prayer. It runs to nineteen benedictions on weekdays, praises, petitions and thanksgivings in a set order, and to a shorter form on the Sabbath and festivals, when the middle petitions are replaced by a single benediction on the holiness of the day, since one does not ask for one's needs on days of rest and rejoicing.
Its structure is deliberate and old: it opens with three benedictions of praise, closes with three of thanksgiving, and places the requests in between, on the model, the rabbis said, of a servant who first praises the king, then makes requests, then takes respectful leave. The tradition ascribes the ordering of the benedictions to the assembly at Yavneh under Rabban Gamliel after the destruction of the Second Temple, when fixed communal prayer came to stand in for the sacrifices that could no longer be offered. Recited three times daily, silently and then, in congregation, repeated aloud by the prayer leader, the Amidah is the armature on which the whole of the rabbinic liturgy is built.