The Maitreya Upanishad, which is regarded as one of the Sannyasa Upanishads, gives two interesting reasons as to why a Sannyasi can not perform Sandhya worship. Among which,one reason is related to impurities associated with birth/death.
To meditate on the One is almsfood and on the many is proscribed food. For almsmen is prescribed almsfood that is in accord with the directions of the teacher and of the scriptures.
"A sage should leave his native land right after he has renounced. He should live far away from his own, like a thief just released from jail.
"Pride is his son and wealth his brother. Delusion is his house and lust his wife. A man is freed, there is no doubt, as soon as he abandons these.
Delusion, our mother, has died. Enlightenment, our son, is born. With a double impurity at hand, how can we per- form the twilight worship?
"The sun of consciousness always shines brightly in the sky of our hearts. It does not set and it does not rise. How can we perform the twilight worship?
Maitreya Upanishad Chapter 3.
Now of course, these examples are symbolic, as the real mother has not died nor a son is actually born. Still, the two impurities are assumed (or stated) to exist in a Sannyasi's life forever. And, that's why he can never perform Sandhya worship.
However, in normal circumstances, for all persons, these impurities (Asaucha) exist but only for few days (from 10 to 30 days depending on Varnas).
So, i am curious to know:
Question- Why certain birth/death related impurities are considered to be as ever lasting for Sannyasis when normally they exist only for a few days?
There must be some deeper significance behind saying all these and which i am failing to understand.