Translation: Ishaq bn AbdurRaheem Aboo Aamir Al-Atharee
Al-Imaam Ahmad - rahimahullaah - said in his book, Usool Sunnah, in the narration of 'Abdoos bn Maalik al-Attaar, rahimahullaah:
أصول السنة عندنا التمسك بما كان عليه أصحاب رسول الله...وترك الخصومات...وترك المراء والجدال والخصومات في الدين
'Foundations of Sunnah with us are: holding to what the Companions of the Messenger of Allaah were upon...shunning discordancy...shunning argumentation, disputation and quarreling about the Deen...'
Al-Allaamah Rabee bn Umayr al-Madkhalee - hafidhahullaah - explained in his Shar'h Usool Sunnah, Daar Minhaaj Edition (2007), p.11:
'Do not be too much of arguments, do not dispute (with anybody) except where you know there is benefit for he that seeks it - someone who wants to engage you in a discussion in order to arrive at the truth, as you are sure of, then go ahead with him. Allaah says (in the interpretation of the meaning) 'argue with them in the best of manners (Nahl: 125)'. As for when someone wants to cause you to slip or contends with you or wants to dominate you (in a discussion), then do not argue with such a person. That is from the blameworthy disputation and is tantamount to quarrelling about the Deen, thus a blameworthy discordancy.'