wswrwb the Source is Ibn al-Jawzi's Kitab Akhbar al-Sifat - recently published from the Istanbul library manuscript. I can scan up the Arabic for you later, inshaAllah. I intend to put up more from this book some time soon.
Ibn al-Jawzi al-Hanbali has an interesting and rather unique answer to this question which I thought I would post here. The Imam says in Kitab Akhbar al-Sifat: If someone should ask why the Messenger of Allah summoned [people] to something by means of expressions that are seemingly anthropomorphic, it should be pointed out that sense experience conditions the way people think to such an extent that they are scarcely able to conceive what lies beyond the realm of the senses, and the reason for that lies in the natural human affinity (mujanasa) for things temporal (hadith) . [This explains why] some people worship the stars and attribute beneficial and harmful influences to them; [why] some people worship angels, some the sun, some Jesus, some 'Uzayr, and some the cow, and [why] the majority of people [worship] idols. [People] have a natural affinity for those things whose existence can be apprehended through the senses. It was for this reason that [the Children of Israel] said to Moses: "Make us a god." If revelation (shara'i) had been given [to the Prophet] in the language of pure transcendence (bi't-tanzih al-mahd), it would have had to express itself through negation and denial (an-nafy wa'l-jahd). When they said [to the Prophet]: "Describe your Lord to us," the verse: "Say, He is God the One" was revealed. Had [the Prophet] merely said that He is not a body (jism) , or an atom (jawhar) , or an accident ('arad) ; that He is without length or breadth; that He neither occupies space nor is encompassed by space; that none of the six spatial relations apply to Him; that He neither moves (mutaharrik) nor is at rest (sakin); and that He is not accesible to the senses (ahsas) , etcetera, - [they would not have understood]. Had [the Meccans] only said' "Limit your use of [the language of] negation by making concrete the One whose worship you summon us [instead of relyin solely on the language of] negation, otherwise you call us to something that has no reality [for us" - they would have spoken the truth]. It was for this reason that God applied to Himself expressions (asma') which they could comprehend - such as, for example, hearing, seeing, understanding, expressing anger, building the House, and designating the [Black] Stone as the hand [of God] which can be touched, not to mention such expressions as face, hands, foot, ascending the Throne ['istiwa] and descending - all for the purpose of rendering His existence capable of affirmation. From the vantage point of revelation (shar') this is more important than an emphasis on transcendence (tanzih) , although the latter is an essential part of it. It was for this reason that the Prophet once asked a slave-girl: "Where is God?" On another occasion when he was asked whether God laughs he answered in the affirmative. However, while [the Prophet] affirmed God's existence by appealing to images (suwar) drawn from sense experience, supposing such representations (tashbih) [to be literally true] was forbidden by the verse: "There is nothing like unto Him."
