The following is an excerpt from Srila Gurudeva's book, "Harmony":
Anandini dasi: How can I stop myself from criticizing?
Srila Gurudeva: You can criticize yourself, but not others. This is an offense, and bhakti [love] will go away. Be careful.
Vrndavana, India: August 9, 2009
Prakasatma dasa: How can I curb my tendency to always speak prajalpa [nonsense] and criticize others?
Srila Gurudeva: You can do so by always being in sadhu-sanga and hearing harikatha. Pariksit Maharaja had no time to speak with anyone, or to sleep or eat or drink. He was drinking only the nectar of Krsna-lila. Sadhu-sanga is the best medicine. Chant the holy name in sadhu-sanga, and don't associate with persons who are chattering and pattering.
Read books and engage your mind at all times. If the mind is not engaged by you, then it will automatically engage itself in bad things. The mind wants something to eat, so we should give it harikatha - as much as you can hear and chant and meditate on.
Paris, France: June 30, 2009