For his mercy endureth for ever (Ps. 136:1)
A refrain, perhaps sung by a whole body of singers or by the congregation, emphasizing the message by repetition (see Ezra 3:10, 11; II Chron. 7:3). Among the many facets of the Hebrew word translated "mercy" are loyalty and loving-kindness.
Thou shalt have no other gods before me (Ex. 20:3)