It is narrated that when Ameerul Momineen (a.s.) was returning
from the Battle of Siffeen, he wanted relieve himself. Some
hypocrites said: “We would go and see his privates.” Ameerul
Momineen (a.s.) summoned Qambar and asked him to call out to two
trees at a great distance: “Successor of Muhammad, messenger of
Allah commands you to come and join together.”
Qambar said: “O Ameerul Momineen (a.s.), would my call
reach the trees?” Imam (a.s.) said: “That God, Who has made your
eyes seeing in such a way that you can see the sky, He would make
your voice reach those trees.” So, Qambar went and called out as the
Imam had ordered. Suddenly he saw that those two trees rushed and
embraced each other like two friends.
Some hypocrites said: “Ali Ibne Abi Talib (a.s.) is a sorcerer
like his cousin, Muhammad. We shall go around and see his
privates.”
Ameerul Momineen (a.s.) said to Qambar: “These hypocrites
intend to deceive and they think that I can’t conceal myself without
these two trees. Qambar, go to the trees and say: Successor of your
Prophet orders you to go back to your respective places.” He went
and said this and those trees returned to their previous places. His
Eminence also went to attend the Nature’s call.
However, no matter how much the hypocrites tried to see they
were unable to see anything. When they glanced in another direction they were able to see. And again when they glanced at His
Eminence, they did not see him. This was repeated a number of
times till His Eminence returned. When he did so the hypocrites
went to the place where His Eminence had retired, but did not see
anything
Behaarul Anwaar, vol. 24, p. 29
Isbaatul Wilayah (Part One) – Ayatullah AliNamazi Shahroodi (r.a.)