In the Name of Allah, The Most Merciful, The Bestower of Mercy.

If you see someone arguing in a good manner seeking to benefit, clarify for him. He has doubts, therefore, remove them through gentleness, wisdom and fine admonition. However, if he is just trying to debate for the sake of it, do not argue with him, as he is not interested in the truth and you won’t attain a (fruitful) outcome.

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Sharh Usul As-Sunnah Lil Imam Ahmad p36