Imaam Ash-Shaafi’ee (d.204) said, “My ruling regarding the people of Kalaam (theological rhetoric) is that they should be beaten with palm leaves and shoes and be paraded amongst the kinsfolk and the tribes with it being announced, ‘This is the reward of the one who abandons the Book and the sunnah and turns to theological rhetoric (kalaam).“
[Sharh 'Aqeedatut-Tahaawiyyah og Ibn 'Abdil-'Izz, p. 75]
Ibn ‘Abdil-Barr said, “The people of Fiqh and Aathaar in all the various towns and cities are agreed unanimously that the Ahlul-Kalaam (People of theological rhetoric) are but Ahlul-Bida’ waz-Zaigh (the People of Innovations and Deviation). And they are not considered, by all of the above, to be amongst the ranks of the Scholars (in truth).“
[Reported by Ibn Qudaamah in his Burhaan Fee Bayaanil-Qur'aan]
Imaam Ash-Shaafi’ee said, “That a person is pout to trail with everything that Allaah has forbidden, besides Shirk, is better than that he looks at Kalaam (theological rhetoric).“
Imaam Ash-Shaafi’ee also said, “If people knew what (misleading and destructive) desires are contained within theological rhetoric they would certainly flee from it as they would from a lion.“
Imaam Ash-Shaafi’ee also said, “Whoever showed boldness in approaching theological rhetoric will never prosper.“
[Reported by Ibn Qudaamah in his Burhaan Fee Bayaanil-Qur'aan]
One of the Scholars of Ash-Shaash said:
“Every knowledge except that of the Qur’aan is a pre-occupation
Except for the Hadeeth and Fiqh (understanding) of the deen
Knowledge is only that about which it is said,
‘Haddathanaa…” (So and so narrated to us (a hadeeth))
And what is besides that
Are but whisperings of the Shaytaan (Devils)”
Aboo Yoosuf, the companion of Aboo Haneefah, said, “Whoever sought knowledge by Kalaam (theological rhetoric) will turn a heretical apostate.“
Imaam Ahmad (d. 241) said, “The person of theological rhetoric will never prosper. And never do you see anyone looking into theological rhetoric except that in his heart is a desire for creating mischief.“
[Both the above narrations are reported Ibn Qudaamah in his Burhaan Fee Bayaanil-Qur'aan]
[Taken from "Foundations Of The Sunnah" Pp. 16-17]