Sutra:
159. pERRukkup palakAlum vENumenRu ninaikkil upAyam nazhuvum.

Meaning:
If it is thought that to achieve the goal seeked that this mantra has to be recited for a very long time, then this means will not work.

Sri PBA Swami's Sarartha Deepikai:
Therefore, this mantra should be repeated for the above said reasons only. If, instead, it is recited thinking that long recitation is required to reach the goal, then that siddhOpayam (the means also being the end) which does not tolerate any other means will slip away, just like the brahmAstra that had tied Sri Hanuman slipped away when a rope made of jute was also used to tie him.

Thus far the meanings of the first part of the Dvaya mantra have been explained.