In Insights of the Daf for Berachos 27 you have on the site:
>>2) REBBI ELAZAR BEN AZARYAH ASKED HIS WIFE
QUESTION: Rebbi Elazar ben Azaryah refused to accept a leadership position until he asked his wife. Why did Rebbi Elazar ben Azaryah need to ask his wife? What were his doubts?
ANSWER: RAV YONASAN EIBSHITZ in YA'AROS DEVASH (cited in MAHARATZ CHAYOS) explains that the Gemara in Kesuvos (61b) states that a man who works as a donkey driver (whose conjugal obligation to his wife is once a week) who desires to become a camel driver (whose conjugal obligation is once every thirty days) must ask his wife for permission. His career-change will cause a decrease in the frequency of her conjugal rights (Onah), and she must give her permission first.
The Gemara there states that a Talmid Chacham's conjugal obligation is once a week, "from Shabbos to Shabbos." A Nasi's conjugal obligation is once a month (as is stated in Avos d'Rebbi Nasan). The choice to become a Nasi would affect his wife, and therefore Rebbi Elazar ben Azaryah needed to ask her for permission!<<
Where is this Avos dRebbi Nasan?
Sruli Schorr
That is a very good question.
The Ya'aros Devash that quotes this statement of Chazal is in Part 2:18, DH Amnam. The statement is also quoted by the Chasam Sofer (EH 1:151, DH Os Kasav) - although his source may very well be the Ya'aros Devash.
The Pischei Teshuvah (EH 76:3) already pointed out that he found no such source in Avos d'Rebbi Nasan - or elsewhere for that matter.
Some (Meichla d'Asvasa #108, cited in an appendix to the Mechon Or ha'Sefer printing of Ya'aros Devash) point out that the source for this assertion may be the verse in Esther (4:11), "I have not been called to the king these 30 days..." - which implies (see Shemos Rabah 15:6) that if the king indeed loved her, she would expect him to call her back after 30 days .
Best wishes,
Mordecai Kornfeld