Ana BeKhoach is a short mystical prayer of seven lines and forty-two words, the initial letters of which are read as encoding a forty-two-letter name of God, one of the hidden divine names of the Kabbalistic tradition. Traditionally ascribed to a sage of the early rabbinic period, though its composition is more likely medieval, the prayer petitions God, by the power of that great name, to release, protect and restore his people. It entered the liturgy through the influence of the Kabbalists of Safed in the sixteenth century and is recited at several points, in the morning service, in the counting of the days between Passover and Shavuot, and in the welcoming of the Sabbath, and it is used devotionally with attention to the letter-name concealed in it. The prayer is a clear example of how Kabbalistic ideas about the power of the divine names entered and shaped the ordinary prayer book used far beyond mystical circles.