Hakeemul Ummah Hazrat Moulana Ashraf Ali Thaanwi Sahib رحمه الله has said that it is observed that Noor (a lustre) cascades from the speech of the Ahlullāh, whilst darkness drapes the speech of the deviates. The words of the Awliyaa are straightforward. They do not use flowery language, but studying their works produces Noor in the heart. On the other hand, those who are not observant of Shariah, no matter how polished their words may be, these leave a darkness in their wake, regardless of what they say being related to Deen. Since the words are theirs, therefore darkness is a corollary of their words. Whoever has the slightest spiritual perception can sense this difference without doubt.
In the speech of the Ahlullāh, there is Noor which cannot be found in the non-Ahlullāh. The effect of one’s heart falls on the audience, not the effect of words. One may have acquired the knowledge of words; the need is for the words to permeate the heart.
(SOURCE: ADAPTED FROM THE SPEECH OF THE AHLULLĀH by Hakeemul Ummah Hazrat Moulana Ashraf Ali Thaanwi Sahib رحمه الله)