The Bhagavad Gita with Commentaries of Ramanuja, Madhva, Shankara and Others.
Bhagavad Gita 2.4
http://www.bhagavad-gita.us/articles/617/1/Bhagavad-Gita-24/Page1.html
By Bhagavan Sri Krishna
 

Text 4

arjuna uvaca
katham bhismam aham sankhye
dronam ca madhusudana
isubhih pratiyotsyami
pujarhav ari-sudana

Translation

Arjuna said: O killer of enemies, O killer of Madhu, how can I counterattack with arrows in battle men like Bhishma and Drona, who are worthy of my worship? 

Commentary by Srila Prabhupada 

Respectable superiors like Bhishma the grandfather and Dronacarya the teacher are always worshipable. Even if they attack, they should not be counterattacked. It is general etiquette that superiors are not to be offered even a verbal fight. Even if they are sometimes harsh in behavior, they should not be harshly treated. Then, how is it possible for Arjuna to counterattack them? Would Krishna ever attack His own grandfather, Ugrasena, or His teacher, Sandipani Muni? These were some of the arguments offered by Arjuna to Krishna.

Commentary by Sri Visvanatha Cakravarti Thakur

"According to scriptures of dharma, not respecting those worthy of worship is a cause of bondage: pratibadhnati hi sreyah pujya-puja-vyatikramah. Therefore I withdraw from fighting. How can I kill them?" The form prati yotsyami (parasmaipada) is used instead of the form prati yotsye (atmanepada, for oneself).

"But those two elders are fighting. Are you not able to fight against them?"

"No I cannot do so, for they are worthy of worship (pujarhau): I should offer flowers to their feet in devotion rather than sharp arrows in anger. O friend Krishna! Even you injure only the enemies in battle, and not your own guru Sandipani Muni or your friends the Yadus, O Madhusudana, killer of Madhu!"

"But I am a descendent of Madhu, therefore called Madhava, in the ancient lineage of the Yadu dynasty. How could I have killed Madhu?"

"No, 1 do not mean that Madhu. I am speaking about the demon named Madhu who was your enemy (ari sudana)."