Abraham Robinson and Arend Heyting had mutual respect (though holding differing philosophical views on the nature of mathematics). Heyting repeatedly expressed admiration for Robinson's work; see for example here. However, I was unable to find any information of what Robinson may have thought of Heyting's work.
I did find a 1968 essay by Robinson entitled Some thoughts on the history of mathematics which was "Dedicated to A. Heyting on the occasion of his 70th birthday", but it contains no mention of Heyting's work.
Has Robinson ever discussed Heyting's mathematics?