(Anglo-Saxon, bed, a prayer). When little balls with a hole through them were used for keeping account of the number of prayers repeated, the term was applied to the prayers also. (See Beadsman.)
To count one's beads.
To say one's prayers. In the Catholic Church beads are threaded on a string, some large and some small, to assist in keeping count how often a person repeats a certain form of words.
To pray without one's beads. To be out of one's reckoning. (See above. Baily's Beads. When the disc of the moon has (in an eclipse) reduced that of the sun to a thin crescent, the crescent assumes the appearance of a string of beads. This was first observed by Francis Baily, whence the name of the phenomenon.
St. Cuthbert's Beads. Single joints of the articulated stems of encrinites. They are perforated in the centre, and bear a fanciful resemblance to a cross; hence, they were once used for rosaries (beads). St. Cuthbert was a Scotch monk of the sixth century, and may be called the St. Patrick of the north of England and south of Scotland.
St. Martin's beads. Flash jewellery. St. Martins-le-Grand was at one time a noted place for sham jewellery.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894