Ibn Abdul Barr said, and istawaa is istiqraar in highness (uluww) [i.e. He has settled in being high], and this is what Allaah informs us, 'In order that you may mount firmly (tastu) on their backs, and then may remember the favours of your Lord when you mount (istawaytum) thereon...' (43:13), and Allaah said, 'and it rested (wastawat) on Mount Judi' (11:44), and He the Exalted said, 'so when you embark (istawayta) and those with you on the ship' (23:28). [i.e. all the examples show itiwaa to mean coming to rest in an elevated position]
....and as for their using as proof the narration of Ibn Abbaas about the saying of Allaah, 'The Most Merciful istawaa upon the Throne' -'He conquered/overcame (istawlaa) all His opponents and He is everywhere.'
Then the answer is that this hadeeth is munkar to Ibn Abbaas (RA) and is transmitted by unknown and weak narrators ....(takhreej ommitted).... and they (i.e Mu'tazila who narrated this hadeeth) do not accept the individually narrated tradition so how can they permit depending upon the likes of this hadeeth, if they had sense and were just? As for what they hear Allaah say, 'And Pharoah said, "O Haman! Build me a tower that I may arrive at the ways - the ways of the heavens, and I may look upon the God of Moses but verily I think him to be a liar."' (40:36-37) then this lends evidence to the fact that Moses (AS) used to say that verily my God is above the Heaven and Pharoah thought he was a liar.
And also from the proofs that Allaah is over the Throne , above the seven heavens is that the Believers in Tawheed (muwahhideen), all of them, arabs and non-arabs, when a matter concerns them, or a difficulty befalls them, they raise their faces to the heaven, and direct their raised hands to the heaven, seeking succour from Allaah, their Lord. And this is common amongst the general masses as well as the elite (khaasa)....And the Prophet (sallallaahu `alaihi wasallam) said to the slave girl whose master wished to free her if she was a believer, so the Messenger (sallallaahu `alaihi wasallam) tested her asking her, 'where is Allaah?' So she pointed to the heaven. Then he asked, 'who am I?' So she said, 'you are the Messenger of Allaah'. So he said, 'set her free for she is a believer.' So it sufficed the Messenger of Allaah (sallallaahu `alaihi wasallam) from her, her raising her face to the heaven and was content with that, not requiring anything else.
And as for their seeking support in the saying of Allaah, 'their is no secret discourse of three except that he is the fourth' then this is not a proof for them according to the literal sense of this verse. Because the scholars from the companions and taabi'een from whom the explanation of the Qur'aan is taken from, said in explanation of this verse: He is over the Throne, and His Knowledge is in every place, and no one from amongst them, whose saying is depended on, differed on this. Ad-Dahhaak said about His saying, 'their is no secret discourse of three except that He is the fourth...' - 'He is over His Throne, and His Knowledge is with them, wheresoever they may be.' And it has reached me that Sufyaan ath-Thauri said something similar. Ibn Mas'ud (RA) said, 'Allaah is over the Throne, and nothing is hidden from Him of your actions'"