The Jesus Prayer in some form is certainly the most important and widely used prayer with the prayer rope. The various forms of the prayer include:
'Lord Jesus Christ, Son of God, have mercy on me, a sinner.'
'Lord Jesus Christ, Son of God, have mercy on me.'
'Lord Jesus Christ, have mercy on me.'
But other prayers are also said on the prayer rope:
'Most-Holy Theotokos, save me, a sinner.'
'Holy Angel, my Guardian, pray to God for me, a sinner.'
'Saint of God, N., pray to God for me, a sinner.'
'All ye Saints, pray to God for me, a sinner.'
The famous prayer rule called the "Optina 500" gives the following rule to be said each day:
300 Jesus Prayers (i.e. 3 ropes of 100 knots each)
100 'Most-Holy Theotokos....' (i.e. 1 rope of 100 knots)
50 'Angel of Christ, my Guardian...' (i.e. the first half of one prayer rope)
50 'All ye Saints of God...' (i.e. the second half of one prayer rope)
The prayer rope is basically an aid to count prayers, whatever short prayers one desires to say.
Fr David Straut