It is said:
«لا تَنْظُرْ اِلى مَنْ قالَ، بَلِ انْظُرْ اِلى ما قالَ».
Do not consider the speaker; rather consider his (her) utterance.
But its full observance is not possible for anybody, because everybody assumes the speech as the product of speaker's being. In view of material tools, speech is the same transformation in man's energies. Chemical energy is transformed into mechanical energy in the cells and mechanical energy to acoustic energy.
And in view of spiritual contents and materials, it is the product of thoughts, education, environment, knowledge, attributes, and spiritual states.
Thus, any speech has the same color of its speaker, and carries the speaker's attributes, either his spirituality or his ugly and bad attributes, and on this account, when an utterance is issued by a virtuous individual, all windows of human spirit are opened to it, and all existence of man receives it.
And in contrast, a speech uttered by an impure and evil person faces with the unconscious negative reaction of the hearer, and the windows of his spirit are closed to it.