Devekut, Hebrew “cleaving,” the communion with God, is derived from the Hebrew word davak, meaning being devoted to God. The Talmud asks how can a man cleave to God as he is commanded (Deuteronomy 4:24)? The response is given, by helping scholars (B.Ket. 111b) or emulating God’s attributes (B.Sotah. 14b). The concept is much used in Kabbalistic literature where devekut is perceived as the highest step on the spiritual ladder by which the mystics embrace the lower sephiroth (emanations) in his search for communion with the Divine. It is generally agreed that devekut in the world is fleeting and incomplete; since it is thought that only after death can true devekut be achieved. In Hasidism, the concept and attainment of devekut is very important. A.G.H.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p.272