When others criticize you with their tongues, they bring out the dirt and gunk of their minds. You get purified by their tirades. Saibaba (chap19)showed once a sow eating crap to his devotees saying how she cleans the dirt of this world with her mouth and enjoys it. The one who had earlier spewed venom against another devotee felt very ashamed of his deeds. We are all here to do our specified duties allocated by God so lets do our jobs perfectly and be the best tool of God! Focus on the duties and not on others. Praise God and continue to do our jobs in dedication.