Sutra:
146. pirAttiyum avanum vidilum thiruvadigaL vidAthu; thiN kazhalAy irukkum.

Meaning:
Even if Mahalakshmi who is the mediatrix and Narayana who is the all protector let go of the chetana, His divine feet will never let go of them. They have the quality of never letting go those who are attached to them.

Sri PBA Swami's Sarartha Deepikai:
Since it is said that Sriman Narayana's divine feet are seeked instead of saying that Sriman Narayana is seeked, there must be some special quality to the feet in being the means.

This is the fact that, even if Mahalakshmi who was shown as the mediator and Narayana who was shown as the protector in the earlier sutras, let go off the chetana, His divine feet will not. They will never let go those who are attached to them ("vaN pugazh nAraNan thiN kazhal").