Says the Shaykh Abu Ja'far, may Allah have mercy on him: disputation (jadal) concerning Allah is prohibited, because it leads to that which does not befit Him.1 And Imam Ja'far as-Sadiq was asked concerning the saying of Allah the Mighty and Glorious:
“And that thy Lord, He is the goal” (Qur'an 53:42).
He said: When conversation turns towards (a discussion of) Allah, then refrain (from speech). And as-Sadiq used to say: O son of Adam! If a bird were to eat your heart it would not satisfy it! And as for your sight - if the eye of a needle were to be placed upon it, it would be darkened. And you desire (despite such insignificance) to know the sovereignty of the heavens and the earth! If you are truthful here is the sun, one of Allah's creations; fill your eye with it, and then it will be as you say.
And vain disputation is prohibited concerning all matters of faith. The Prince of Believers, on whom be peace, has said: He who seeks after religion by disputation will become a heretic (zindiq)2.
And Imam Ja'far as-Sadiq has said that the people who indulge in vain disputations (ashabu'l-kalam)3 will perish, and the Muslims will be saved. Verily the Muslims are noble (najib, plural Nujaba). Now as for controversy against opponents by means of the word of Allah and the Prophet and the Imams, or by means of the significance of their sayings, it is allowed without restriction to him who is well versed in theology (kalam). But is not permitted (mahzur) to him who is not well versed in it and totally forbidden (muharram).
And Imam Ja'far as-Sadiq said: Controvert the people with my sayings, and if they overcome you by argument, it will be I who will be controverted, not you. It is related from him that he said: Speaking in (defense of) the truth is better than silence in respect of falsehood. And it is related that Abul Hudhayl al Allaf said to Hisham bin al-Hakam: I wish to have a controversy with you on the condition that if you overcome me, I shall adopt your faith; and if I overcome you, you must accept mine. Hisham said: you have not dealt justly with me. Nay, I will have a controversy with you on the condition that if I overcome you, you will accept my faith; but if you overcome me, I shall refer it to my Imam (for a proper answer).4