Letters from Sri Ramanasramam, by Suri Nagamma

What other brahmasthram (divine weapon) is there against a
questioner? If only that weapon is used, the questioner is
silenced.

You may ask, “Who gave the name of ‘brahmasthram’ to
the stock reply of Bhagavan, ‘Find out who you are?’.” Two
or three years back, when a sannyasi boasted about having
read all books on religious matters and began asking
Bhagavan all sorts of questions, he repeatedly gave the same
answer, “Find out who you are.” When the sannyasi persisted
in his meaningless questions and arguments, Bhagavan in a
firm tone asked him, “You have been asking me so many
questions and entering into so many arguments. Why don’t
you reply to my questions and then argue? Who you are?
First answer my question. Then I will give you a suitable
reply. Tell me first who it is that is arguing.” He could not
reply, and so went away.

Some time later, I developed this idea and wrote five
verses on ‘Divya Asthram’ and showed them to Bhagavan,
when he said, “Long ago when Nayana (Ganapati Muni)
was here, Kapali also used to be here. If they wanted to ask
me anything, they would fold their hands first and say, ‘Swami,
Swami, if you will promise not to brandish your brahmasthram,
I will ask a question.’ If during conversation the words ‘Who
are you?’ escaped my lips, he used to say, ‘So you have fired
your brahmasthram. What more can I say?’ They called it
brahmasthram and you are calling it ‘Divya Asthram’.” After
that, I too started using the word brahmasthram. Really, who
is not humbled by that asthram?