The 1975 published version of a 1974 talk at a workshop by Errett Bishop contains the following comment:
"A more recent attempt at mathematics by formal finesse is non-standard analysis. I gather that it has met with some degree of success, whether at the expense of giving significantly less meaningful proofs I do not know. My interest in non-standard analysis is that attempts are being made to introduce it into calculus courses. It is difficult to believe that debasement of meaning could be carried so far."
This was published in
Bishop, E. "The crisis in contemporary mathematics." Proceedings of the American Academy Workshop on the Evolution of Modern Mathematics (Boston, Mass., 1974). Historia Math. 2 (1975), no. 4, 507--517.
Was anyone present at Bishop's lecture who can testify whether Bishop actually made those comments in his oral presentation?
Note 1. As per discussion in the comments: The reason I doubt Bishop actually said that in his oral presentation is because in the ensuing discussion, also published in Historia Math. along with the lecture, nobody challenged Bishop on his comments even though a number of logicians were present. It seems likely that, had he said that publicly, there would have been some reaction and ensuing discussion.
Note 2. This question is primarily concerned with what Bishop said, or more precisely did not say, at the workshop, but since in the comments editors have responded with remarks on the effectiveness of teaching calculus using infinitesimals I would mention that there are many approaches to teaching the calculus, some more effective than others, but one rarely finds people dismissing an approach right out of hand without looking at the details and whether it actually works in the classroom, etc.--that is, except when it comes to true infinitesimal calculus, where everything seems to be allowed. Such a situation, I would argue, is partly the result of an atmosphere of demonisation of Robinson's framework created by the likes of Bishop, Halmos, and Connes. For more details on this aspect of the story see the many published articles here.