You can further empower your friendship amulets by knotting them in accordance with the laws of magic. If the cord binding your bags is knotted nine sacred times, you will have increased greatly the power of the spell. Nine is the number of idealism, altruism, generosity, tolerance, and sacrifice. Here is a rhyme to recite as you bind:

By knot of one, the spell is begun.
By knot of two, it comes true.
By knot of three, so mote it be.
By knot of four, ’tis strengthened more.
By knot of five, the magic is alive. 
By knot of six, this spell shall I fix.
By knot of seven, the planets in heaven.
By knot of eight, I have sealed my fate.
By knot of nine, this work is divine.
So shall it be.
 

You can also make a magic knotted cord to tie around a paper scroll. On the paper might be a written desire, a spell, or a wish expressed to a friend in a letter.